Sign by Sender adds the sender's signature if he/she has been identified as one of the signers.
In the Standard System Demo, the Adobe Sign Agreements table contains two rules. These rules are accessed by expanding the Adobe Sign Agreements table in the left pane, selecting Setup Adobe Sign Agreements, and then selecting the Rules tab:
Edit: Completion actions - convert file and update contract: This rule uses a saved search to run whenever the Status field of an Adobe Sign Agreement record is set as completed. It uses an If-Then-Else action called "Completion actions for contracts" and updates the Status of Contract. It also runs a conversion action to create a new attachment record for the signed documents.
Edit: When status changes to Sent, update linked contract, if any: This rule uses a saved search to run whenever the Status field of an Adobe Sign Agreement record is set as Sent. It uses a linked record action to change the related contract record's status as Pending Signature.
Adobe Sign Agreement records are owned by the sender of the Agreement. Adobe Sign Agreements records are owned by the user whose Login matches the Sender Login field.