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In order to verify that the contents of PDF document has not been edited or forged once it been signed, anyone in the work flow involved need to use digital signature to sign the document. When digitally signing a PDF document, you may need to add more than one signatures on it. There are two situations that you might be involved in. You are the main person in charge that need to sign a PDF document many times. You and others are required to sign the same document many times via transmission. These two situations require the PDF signing tool supports adding multiple signatures to a PDF document by the same or different signers.

Are you looking for such a tool or library for C# applications development that allow users to sign a PDF document many times, especially signing by the same or different signers. Try XsPDF SDK! Our .NET PDF digital signature SDK provides mature C# APIs for signing PDF file multiple times. Meanwhile, the created signatures can be covered by each other or displayed separately. Please note that, only the original signer has the permission or right to change his or her signatures. Thus, the PDF document is strictly kept, authorized, and protected via transmission.

Add Multiple Signatures to PDF in C#

This section provides you with a simple C# example for how to add and place multiple signatures on a PDF document.


//Add first signature
PdfCertificate cert1 = new PdfCertificate("demo1.pfx", "your-password");
PdfSigner signer = new PdfSigner("demo.pdf", cert1);            
signer.ContactInfo = "contact1";
signer.Location = "location1";
signer.Reason = "reason1";
signer.FieldName = "XsPDF Sign1";
signer.PageId = 0;
signer.Rect = new Rectangle(100, 100, 100, 50);
signer.SignatureAlgorithm = SignatureAlgorithm.SHA256;
signer.SignatureShowingType = SignatureShowingType.Description;
signer.Sign("demo.pdf");

//Add second signature
PdfCertificate cert2 = new PdfCertificate("demo2.pfx", "your-password");
signer = new PdfSigner("demo.pdf", cert1);
signer.ContactInfo = "contact2";
signer.Location = "location2";
signer.Reason = "reason2";
signer.FieldName = "XsPDF Sign2";
signer.PageId = 1;
signer.Rect = new Rectangle(300, 50, 100, 50);
signer.SignatureAlgorithm = SignatureAlgorithm.SHA256;
signer.SignatureShowingType = SignatureShowingType.Description;
signer.Sign("demo.pdf");

Notice - If you use the free trial version of .NET PDF Digital Signature SDK, the sign field is showing "XsPDF Signer Trial Version".

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