Check a signed copy
Choose a signed PDF from asSigned. Your browser works out its fingerprint, and asSigned looks for it among the copies it has issued. The file itself never leaves your computer.
The signed PDF
Why this works
When everyone has signed, asSigned records the signed PDF's SHA-256 fingerprint, and keeps that record after it deletes its copy of the document. Any change to a file, however small, changes its fingerprint, so a match means this is the copy that was signed.