Add Digital Signatures on an existing page | Telerik Document Processing

Updated on Apr 24, 2026

Product Version	Product	Author
2021.1.118	RadPdfProcessing	Georgi Georgiev

Description

A common scenario is to replace a temporary page content (a templated text) with a Digital Signature widget. This allows already created PDF documents, e.g. using the Telerik Report Designer, to be modified by adding a Digital Signature on a position defined by the existing content of the document.

Solution

The following example demonstrates the approach of iterating the page content and finding TextFragment elements matching the $CollectSignature text. For each found match, a Signature Field is created and the TextFragment is replaced with a Signature widget. The Rect property is used to position and outline the Signature widget on the page.

csharp

	foreach (RadFixedPage page in document.Pages)
	{
		List<TextFragment> contentToRemove = new List<TextFragment>();

		foreach (ContentElementBase contentElement in page.Content)
		{
			// Find a TextFragment excactly mathcing the $CollectSignature text
			if (contentElement is TextFragment textFragment && textFragment.Text == "$CollectSignature")
			{
				// Create and add Signature Field and Signature Widget
				SignatureField signatureField = document.AcroForm.FormFields.AddSignature("SignatureFieldUniqueName");
				SignatureWidget widget = signatureField.Widgets.AddWidget();

				Point location = new Point(textFragment.Position.Matrix.OffsetX, textFragment.Position.Matrix.OffsetY - textFragment.FontSize);
				widget.Rect = new Rect(location, new Size(DesiredWidth, DesiredHeight));

				page.Annotations.Add(widget);

				// Indicate the TextFragment to be removed
				contentToRemove.Add(textFragment);
			}
		}

		foreach (TextFragment contentElement in contentToRemove)
		{
			page.Content.Remove(contentElement);
		}
	}