Locate the PDF file to be signed, and double-click it to open it. You can also open the reply reader first, then open the location where the file is saved on the desktop, find the file, and click Open. This method is a bit troublesome. Then find the PDF signature on the page that opens, and then check the Create Signature option. You can choose to import a picture directly or draw a signature, choose the latter, then draw a custom signature that has been approved, then name it, or add password protection. Then double-click Apply Signature to get the following custom signature.

Note that this signature cannot be changed by others, because the password is set, so the signature can be protected.