RCW 64.08.100

Any person who is otherwise competent but is physically unable to sign his or her name or make a mark may make an acknowledgment authorized under this chapter by orally directing the notary public or other authorized officer taking the acknowledgment to sign the person's name on his or her behalf. In taking an acknowledgment under this section, the notary public or other authorized officer shall, in addition to stating his or her name and place of residence, state that the signature in the acknowledgment was obtained under the authority of this section.