I received a 1042-S Code 15, how do i report this in Turbo Tax. I am a US citizen living in Canada.

To record your tax withholdings, in TurboTax online program, please use these steps:

1.  Sign back into the program and select Take me to my return 

2.  At the right upper corner, in the search box, type in estimates paid and Enter

3.  Select Jump to estimates paid

4. On the screen, Estimates and Other Income Taxes Paid, select the right section to enter information 

By the way, if you are a US citizen you should NOT have received a 1042S.  You should tell the payer that you are a US citizen.  The form is for "foreign persons," which does not include US citizens.

Here are IRS instructions for Form 1042-S