I set this shipping method up several ways, and it never shows up when Canadian orders are placed. I ship from US via USPS and have added Canada (and tried 'All Countries') too, and tested many variations of allowable cost, weight, etc, and nothing I do will show this shipping method during checkout.
 
The only method that I can get to work is USPS Priority Mail International, which is cost prohibitive for customers only spending a few dollars.
 
Any suggestions?

I agree, it's frustrating the US postal service doesn't make it easy to ship by 1st class mail which is much cheaper. It's not ViArt, it's the skewed wisdom of the post office.
 
I downloaded the USPS free "shipping Assistant" which prints stick-on labels ready for customs. It still needs postage. Currently I'm just using stamps (get lots of $4.90 stamps if you use this approach!), but you can also use stamps.com or one of the other paid services to print postage (I think one of these services does print 1st class int'l labels directly).
 
At least my labels look professional and I don't have to take packages to the post office or fill out those tedious green stick-on declarations... and the customer avoids the expense of priority mail.