You are entering the distribution as SSA income. You are then entering any foreign (Canadian) tax paid on that income under Foreign Taxes as "Other Taxes Paid" to get the credit for the tax paid on such distribution.
To enter the NR4, treat it as if it is a SSA-1099 and enter it in the Retirement Plans and Social Security section, under ‘Social Security (SSA-1099, RRB-1099)’.
Then, go to the Deductions and Credits section and select Foreign Taxes under ‘Estimates and Other Taxes Paid’ to enter any foreign tax you already paid to Canada on that income.
For more info specific to the US/Canadian tax treaty, please see http://www.irs.gov/pub/irs-pdf/p597.pdf
**Say "Thanks" by clicking the thumb icon in a post
**Mark the post that answers your question by clicking on "Mark as Best Answer"
