Add a new document and on the Who is signing? screen, choose Others In Person.
While viewing your document you can tap or click on any page to add text, signatures, initials, dates, and other fields.
Signing in Others In Person mode is similar to Just Me mode, except you (or your signer) will always get prompted to enter signatures, initials, and name fields. Previously used signatures, initials, and names will not be remembered when in Others In Person mode.
These videos show some examples of how to fill and sign documents: