A notarizing officer must execute a written certificate attesting to the performance of a notarial act. This certificate may be inserted on or appended to the notarized document (see § 92.17 regarding the fastening of sheets). The certificate evidences the performance of the notarial act. Failure to execute this certificate renders the notarial act legally ineffective. Each notarial act should be evidenced by a separate certificate; two or more distinct notarial acts should not be attested to by one certificate.