In the expense claim submission process, can you add a step that adds digital signatures to the PDF coversheet?

By virtue of the employee submitting the claim, I would like that to add their digital signature to the cover sheet, then when the manager approves it should add their signature. So when the expense claim is approved and finalized, the PDF export shows a signed coversheet.

Also, if an expense claim gets sent back to the employee for further edits, their original signature is removed and is blank until the correct edits have been made.