A notary must sign the notarial certificate using the same name that is listed on the commission issued by the secretary of state. However, as long as the name matches, the signature of the notary may be printed, written, typed, stamped, etc.
The individual signing the document may sign in whatever manner he/she chooses. The name or manner of signing used by the signor is not the responsibility of the notary public. However, the notary public does have a responsibility to make sure that the information contained in the notarial certificate is accurate. For example if John Doe appears before a notary public and signs the instrument with an “X” the notary public should still state in the notarial certificate that John Doe personally appeared on a given date.