Hi Lucien Lacroix,
Welcome to Auctiva! As you have probably noticed already, Auctiva cannot be used to post to eBay Canada, however, we have a number of Canadian customers who use our site to post their eBay.com(US) and other listings.
Since the eBay.com(US) listing for is designed primarliy for use by sellers located in the US, as a Canadian user, you cannot enter your postal code for use with calculated shipping, nor select Canada specific shipping services, such as Canada Post. Therefore, to post your eBay.com(US) listings through Auctiva, you must specify "Flat Rate Shipping" and use the generic shipping options like "Standard Flat Rate", etc.
The other trick to creating your listings in this manner is that, since you are using the eBay.com(US) lister page, you must treat shipping to the United States as your domestic shipping option and treat shipping to Canada as an international shipping option.
I hope this information proves useful. If you have any additional questions or concerns pertaining to Auctiva, please file a support request using the appropriate link on our help page:
http://www.auctiva.com/free-auction-software-help/help.aspx-Mike
