---
title: "Add visible digital signatures in C# | Nutrient .NET SDK"
canonical_url: "https://www.nutrient.io/guides/dotnet/csharp/editor/add-visible-signature-to-pdf/"
md_url: "https://www.nutrient.io/guides/dotnet/csharp/editor/add-visible-signature-to-pdf.md"
last_updated: "2026-10-08T00:00:00.000Z"
description: "How to add visible digital signatures to a PDF using Nutrient .NET SDK."
---

# Adding visible digital signatures to a PDF document

Use visible digital signatures to combine visual signoff with cryptographic integrity.

Common use cases include:

- Contract signing workflows

- Document approval systems

- Authenticated signoff pipelines

- Branded signature appearances

Unlike invisible signatures, visible signatures render a signature area on the page using text or images.

[Download sample](https://www.nutrient.io/downloads/samples/csharp/add-visible-signature-to-pdf.zip)

## How Nutrient helps

Nutrient.NET SDK handles signature field operations, appearance rendering, and cryptographic signing.

The SDK handles:

- Signature field dictionaries and appearance streams

- PKCS#12 certificate loading and key extraction

- Appearance customization and font rendering

- Byte range calculations and signing internals

## Complete implementation

This example adds a visible signature field and signs it with different appearance options:

```csharp

using Nutrient;

```

## Creating a signature field

Create a signature field at the target location before signing.

In this sample:

- The document opens in a [using statement](https://learn.microsoft.com/dotnet/csharp/language-reference/statements/using).

- The field name is `ApprovalSignature`.

- The position is `(100, 700)`.

- The size is `200 × 50`.

The field acts as the visible placeholder for the signed appearance:

```csharp

using (Document document = Document.Open("input.pdf"))
using (PdfEditor editor = PdfEditor.Edit(document))
{
    PdfPage page = editor.PageCollection.First?? throw new InvalidOperationException("The document has no pages.");

    editor.FormFieldCollection.AddSignatureField(
        "ApprovalSignature",
        page,
        100.0f, // x
        700.0f, // y
        200.0f, // width
        50.0f   // height
    );

    editor.SaveAs("output_document_with_field.pdf");
}

```

## Signing with auto-generated appearance

Sign the field with metadata-driven text.

In this sample:

- `DigitalSignatureOptions` sets certificate and signer metadata.

- `Document.Open("output_document_with_field.pdf")` opens the PDF before signing.

- Setting `UseAutoGeneratedText` to `true` uses signer metadata in the appearance.

- Setting `ShowValidationMark` to `true` adds a validation indicator.

- `SignField(document, outputPath, fieldName, options, appearance)` signs `"ApprovalSignature"`.

```csharp

using (Signature signer = new Signature())
using (Document document = Document.Open("output_document_with_field.pdf"))
{
    using DigitalSignatureOptions options = new DigitalSignatureOptions();
    options.CertificatePath = "certificate.pfx";
    options.CertificatePassword = "Nutrient answers all your document needs";
    options.SignerName = "John Doe";
    options.Reason = "Final Approval";
    options.Location = "New York";

    using SignatureAppearance appearance = new SignatureAppearance();
    appearance.UseAutoGeneratedText = true;
    appearance.ShowValidationMark = true;

    signer.SignField(
        document,
        "output_signed_visible.pdf",
        "ApprovalSignature",
        options,
        appearance
    );
}

```

## Signing with a custom image

Use an image-based appearance for handwritten signatures or logos.

In this sample:

- `Document.Open("output_document_with_field.pdf")` opens the PDF before signing.

- `ImagePath` points to the signature image file.

- The image renders inside field bounds.

- Setting `ShowValidationMark` to `true` keeps the validation indicator visible.

- `SignField(document, outputPath, fieldName, options, appearance)` applies the digital signature.

```csharp

using (Signature signer = new Signature())
using (Document document = Document.Open("output_document_with_field.pdf"))
{
    using DigitalSignatureOptions options = new DigitalSignatureOptions();
    options.CertificatePath = "certificate.pfx";
    options.CertificatePassword = "Nutrient answers all your document needs";
    options.SignerName = "Jane Smith";
    options.Reason = "Review Complete";

    using SignatureAppearance appearance = new SignatureAppearance();
    appearance.ImagePath = "input_signature.jpg";
    appearance.ShowValidationMark = true;

    signer.SignField(
        document,
        "output_signed_with_image.pdf",
        "ApprovalSignature",
        options,
        appearance
    );
}

```

## Signing with custom text

Use custom text when you need workflow-specific signature content.

In this sample:

- `Document.Open("output_document_with_field.pdf")` opens the PDF before signing.

- Setting `UseAutoGeneratedText` to `false` disables metadata-generated text.

- `Text` defines the visible signature content.

- `\n` creates multiline output.

- `SignField(document, outputPath, fieldName, options, appearance)` applies the digital signature.

```csharp

using (Signature signer = new Signature())
using (Document document = Document.Open("output_document_with_field.pdf"))
{
    using DigitalSignatureOptions options = new DigitalSignatureOptions();
    options.CertificatePath = "certificate.pfx";
    options.CertificatePassword = "Nutrient answers all your document needs";
    options.SignerName = "Manager";

    using SignatureAppearance appearance = new SignatureAppearance();
    appearance.UseAutoGeneratedText = false;
    appearance.Text = "Approved by Management\nDate: 2024-01-15";

    signer.SignField(
        document,
        "output_signed_custom_text.pdf",
        "ApprovalSignature",
        options,
        appearance
    );
}

```

## Customizing text appearance

Customize typography to match document or brand requirements.

In this sample:

- `Document.Open("output_document_with_field.pdf")` opens the PDF before signing.

- `FontName` sets the typeface.

- `FontSize` sets text size.

- `TextColor` sets ARGB color values.

- `SignField(document, outputPath, fieldName, options, appearance)` applies the digital signature.

```csharp

using (Signature signer = new Signature())
using (Document document = Document.Open("output_document_with_field.pdf"))
{
    using DigitalSignatureOptions options = new DigitalSignatureOptions();
    options.CertificatePath = "certificate.pfx";
    options.CertificatePassword = "Nutrient answers all your document needs";
    options.SignerName = "Executive";

    using SignatureAppearance appearance = new SignatureAppearance();
    appearance.UseAutoGeneratedText = false;
    appearance.Text = "Approved by Executive Board";
    appearance.FontName = "Times New Roman";
    appearance.FontSize = 14.0f;
    appearance.TextColor = Color.FromArgb(255, 0, 0, 128); // Navy blue

    signer.SignField(
        document,
        "output_signed_styled_text.pdf",
        "ApprovalSignature",
        options,
        appearance
    );
    Console.WriteLine("Successfully signed all documents");
}

```

## Conclusion

Use this workflow to add visible digital signatures:

1. Open the document with `using` statements for automatic resource cleanup.

2. Create an editor and access the page collection.

3. Add a signature field at specified coordinates with defined dimensions (e.g. 100, 700, 200×50 points).

4. The signature field creates a rectangular placeholder for the signature appearance.

5. Sign the field using `Signature` with certificate credentials (PKCS#12 format).

6. Configure signing metadata, including signer name, reason, and location.

7. Create the signature appearance with auto-generated text (set `UseAutoGeneratedText` to `true`) to display metadata.

8. Add validation marks (set `ShowValidationMark` to `true`) to indicate signature validity.

9. Use custom images via `ImagePath` for handwritten signatures or company logos.

10. Use custom text by setting `UseAutoGeneratedText` to `false`, with multiline formatting for workflow-specific approvals.

11. Customize typography with `FontName`, `FontSize`, and `TextColor` using ARGB values.

12. Save the signed document with visible signature appearance and cryptographic integrity.

For related signing workflows, refer to the [.NET SDK guides](https://www.nutrient.io/guides/dotnet/csharp.md).
---

## Related pages

- [Nutrient .NET SDK editor guides](/guides/dotnet/csharp/editor.md)
- [Adding annotations to a PDF document](/guides/dotnet/csharp/editor/add-annotations-to-pdf.md)
- [Adding a custom page to a PDF document](/guides/dotnet/csharp/editor/add-custom-page-to-pdf.md)
- [Adding interactive form fields to a PDF document](/guides/dotnet/csharp/editor/add-form-fields-to-pdf.md)
- [Adding free text annotations to a PDF document](/guides/dotnet/csharp/editor/add-freetext-annotations-to-pdf.md)
- [Adding invisible digital signatures to a PDF document](/guides/dotnet/csharp/editor/add-invisible-signature-to-pdf.md)
- [Adding link annotations to a PDF document](/guides/dotnet/csharp/editor/add-link-annotations-to-pdf.md)
- [Adding redaction annotations to a PDF document](/guides/dotnet/csharp/editor/add-redaction-annotations-to-pdf.md)
- [Adding shape annotations to a PDF document](/guides/dotnet/csharp/editor/add-shape-annotations-to-pdf.md)
- [Adding stamp annotations to a PDF document](/guides/dotnet/csharp/editor/add-stamp-annotations-to-pdf.md)
- [Adding sticky note annotations to a PDF document](/guides/dotnet/csharp/editor/add-sticky-note-annotations-to-pdf.md)
- [Adding text markup annotations to a PDF document](/guides/dotnet/csharp/editor/add-text-markup-annotations-to-pdf.md)
- [Advanced digital signature workflows](/guides/dotnet/csharp/editor/advanced-digital-signatures.md)
- [Detecting and adding form fields to a PDF document](/guides/dotnet/csharp/editor/detect-and-add-form-fields.md)
- [Editing PDF form fields](/guides/dotnet/csharp/editor/editing-pdf-form-fields.md)
- [Editing PDF metadata with Nutrient .NET SDK](/guides/dotnet/csharp/editor/editing-pdf-metadata.md)
- [Filling PDF form fields](/guides/dotnet/csharp/editor/fill-pdf-form.md)
- [Managing PDF page order](/guides/dotnet/csharp/editor/manage-pdf-page-order.md)
- [Merging PDFs](/guides/dotnet/csharp/editor/merge-pdf-into-other-pdf.md)