This is our main tax information forum which deals with topics concerning Canadians living and working in the U.S., U.S. citizens contemplating working in Canada, and all aspects of Canadian and U.S. income tax and related adminstrative issues.
A leeter with a copy of the T form, your SIN, whatever 'proof' you used for non-residency and a cheque for the 15% will do.
After 20 years, I am severely cutting back on responses. Do not ask specifically for my help. There are a few others on this board that can answer most questions. All the best