I believe the rental income should be on line 3 of 6198.
But back up a bit ... are you sure that Form 6198 applies to you? The losses are first limited to your Basis (in your case, $21,051), but if you have At-Risk limits (for amounts Not-At-Risk), that will reduce the allowable losses even further.
https://www.irs.gov/instructions/i6198#idm139991131088368
