Personally I did what it said on the proxy form: "As a shareholder you may attend the meeting and vote, or you may appoint a proxy to attend the meeting. A proxy need not be a shareholder of the Company. The chairman or any other Director of the Company is willing to act as a proxy. If a shareholder wishes to appoint the chairman or any other Director as proxy, they will vote in favour of all of the other resolutions put to the meeting unless otherwise directed. To do so, please write their name or position clearly in the space marked (eg, "Chair of the meeting").
Too late to post it to Dunedin in the current day and age I would have thought, with less than three business days left for delivery now, so you are left with email : "Please return completed proxy form to: Blis Technologies Limited, 81 Glasgow St, South Dunedin, PO Box 2208, South Dunedin 9044 (Attn: [PB]) or by email to [email] no later than 11:00am on Wednesday 25 July 2018."
By email, I assume that they mean attach a scanned signed pdf copy, although personally I have never done it that way.
But remember, "4.If you return this form without directing the proxy how to vote on any particular matter, the proxy will vote as he or she thinks fit."