I have contributions to capital on my k-1, item L. Shouldn't that contribution offset part of my rental income from the k-1? And where do I enter it?

Your capital contributed during the year in section L of the Schedule K-1 increases the cost basis of your share in the LLC/partnership, but does NOT offset your income reported on the K-1. You just have to enter the K-1 in your return. Your capital contribution is not entered anywhere else on your tax return.