Tax Filing for Canadian Dealers?

I feel really stupid posting this and not being able to figure it out myself, but I thought I'd seek some advice from people who have done it in the past before I made any mistakes.

I'm a Canadian resident and am now trying to file my taxes from what I earned at the convention. I'm using the e-tides website to do this at http://www.etides.state.pa.us/

I assume that after I register my enterprise to the system the rest of the filing should be a piece of cake, so my concern is about this first step. Assuming the taxes I am submitting are Sales and Use taxes the next step is to submit my Account Number and Entity ID. The account number is on the form I received when I registered for my PA tax license, so where I'm stuck is what I use for the Entity ID. One of the options is Social Security Number, but as a Canadian and non-US resident I don't have one (I have a Social Insurance Number instead).

If anyone could point out to me how to complete this part of the process that would be *amazing*. I don't want to make any mistakes or do anything illegally. I'm also curious if any Canadians, or other International dealers for that matter, have had issues with filing these taxes or anything after the fact.

Thanks so much for reading and I hope this boring post doesn't bring down the excitement level of the forum too much

- Silent Ravyn