Wash. Rev. Code § 64.08.050
The officer, or person, taking an acknowledgment as in this chapter provided, shall certify the same by a certificate written upon or annexed to the instrument acknowledged and signed by him or her and sealed with his or her official seal, if any, and reciting in substance that the person, or persons, known to him or her as, or determined by satisfactory evidence to be, the person, or persons, whose name, or names, are signed to the instrument as executing the same, acknowledged before him or her on the date stated in the certificate that he, she, or they, executed the same freely and voluntarily. Such certificate shall be prima facie evidence of the facts therein recited. The officer or person taking the acknowledgment has satisfactory evidence that a person is the person whose name is signed on the instrument if that person:
RCW 64.08.050