If you have the "Approver Signature On Check" preference enabled, this is how to add a signature for your payment approvers.
NOTE: In order to add a signature for a user, you need to have permissions to edit users as well as the payment workflow.
Navigate to the User List page and click on the user that needs a signature. This will open a slideover with details of the user. If the user has permission to approve payments, there will be an option to upload a signature in this view. Users with a signature already on file will have their signature displayed, and users without a signature will have text that says "No signature on file".Below this, there will be an "Upload" button that will let you select a signature file to upload.
For best results, we recommend using a .PNG file with a transparent background, and as little extra space around the signature as possible.