When the signer of an instrument cannot write (sign) their name, that person may sign the document by mark.(Civil Code section 14) The requirements for notarizing a signature by mark are as follows: The person signing the document by mark must be identified by the notary public by satisfactory evidence. (Civil Code section 1185) 
Must Be Witnessed
The signer’s mark must be observed by two individuals, who must then sign their names as witnesses on the document. One witness should write the signer’s name next to the mark and then sign their own name as a witness. The witnesses are only confirming that they saw the individual make their mark on the document.
A notary public is not obligated to identify the two witnesses who observe the signing by mark or to have them sign the notary’s journal. However, if the witnesses are serving as credible witnesses to establish the identity of the person signing by mark, then their signatures must be recorded in the notary public’s journal.
Notary Journal
The signer by mark must make their mark in the notary public’s journal. For the mark to be considered a valid signature, it must be witnessed by someone who writes the signer’s name next to the mark and then signs their own name as a witness.
