Digital signing is outside this release
The current Scan to PDF application does not apply or validate certificate-based PDF digital signatures. Scanning a handwritten signature as an image is different from digitally signing a PDF.
Finish the scan before signing
Collect the pages, check their order and clarity, and save the final PDF. Apply a digital signature afterward with a separate signing application that explicitly supports your certificate.
Keep the signed original
Keep an unmodified copy of the signed PDF. Later editing or rescanning does not preserve the original document’s digital signature.
The current Windows product directory lists the supported free applications. It does not offer an installer for this absent product or function.