Rental Property - Mortgage payment for rental

You do not enter mortgage payments made for rental property.  A mortgage payment is a combination of principal and interest.  Only the interest portion of the mortgage payment is deductible as a rental expense.  The principal amount is repayment of the loan and is not a deductible expense.  That applies to rentals as well as itemized deductions.  If your mortgage payment also includes escrow amounts for property tax and insurance, those amounts are also deductible as a rental expense.  Mortgage interest is reported on Form 1098.  If you escrow them, the 1098 also usually shows property tax and insurance disbursements.  They are all reported in the expense section of your rental property.