Agree on your proxy holder who will attend the meeting. Then the proxy can be declared either with email or a document.
Email proxy
Write an email as follows: I, {your registered member name} , a member of Explorers Auckland and entitled to vote, appoint {proxy name}(or by default the chairperson) as my proxy to attend the meeting as my duly authorised representative and to vote for me at the {meeting} of {date}.