PdfSharp class "PdfSignatureField" not working

Building a webapp with C# and Blazor. I have a function in one of my .cs files that uses PdfSharp to generate a PDF based on data from a dictionary.

I'm trying to add a signature field that will allow users to sign the document using a digital certificate. All of the examples of this I can find (which isn't many) seem pretty straightforward, but when I try to replicate them I get an error saying that 'PdfSignatureField' does not contain a constructor that takes X arguments. It doesn't matter if I pass any arguments to it or not, I still get that error.

I found one other person that had this same issue, but the answer was far from helpfulPDFSharp adding digital Signature to PDF not working PdfSignatureField

I'm using:PdfSharp 6.1.1,.NET 8,Visual Studio 17.10

Tried:

PdfSignatureField sigfield = new PdfSignatureField(document);PdfSignatureField sigfield = new PdfSignatureField(document, page, sigrect);PdfSignatureField sigfield = new PdfSignatureField();

Expected:Not to get a constructor error.