As a co-signer, allow me to add notes within the document or in the margins that I am co-signing for the treating therapist to review. It's easier to show my corrections in-line rather than type everything in one box at the end.
When co-signing a note, place comments to the author within the note itself. It's hard to remember all of my feedback and to describe where in the note they need to make changes (having to decline and only being able to type in that one section). It would be easier with several spots throughout the note versus one large spot to enter feedback.