Almost every Appar thevaram ends with the incident of Ravanan lifting the kayilaya malai and siva crushing his ten heads. If I am correct, Sundarar and sambandar's songs will have their signature (meaning their name) in the last (mostly 11th) stanza of the pathigam. But Appar never mentions his name anywhere and his signature is the mention of the ravanan's episode in the 11th stanza.