signing with existing certificates 4

https://wiki-byte.win/index.php/Why_Your_Team_Needs_a_PDF_Signing_API_for_Remote_Signing_Workflows

When you have existing certificates already set up, signing just means telling your system which one to use—no need to generate new keys or go through the whole certificate creation process again. It's a quick way to apply your digital signature to emails, documents, or code, relying on credentials you've already validated. Just pick the right certificate from your list, and you're done.