Where on turbo tax online do you enter rental property depreciation?

In the rental section you ADD AN ASSET and the depreciation is calculated automatically. 

Under the Wages and Income section, scroll down to the Rental section. Once you enter your property set-up, enter your income and expenses, the next section is assets. Your rental property is depreciated over 27.5 years.You will need to separate the land from the building as land is not depreciable.

In the rental and royalty income (SCH E) section of the program, you have four basic sub-sections for rental property. Rental Income, Rental expenses, Assets/Depreciation and Vehicle Expenses.

The property itself and any other assets used in the rental in the production of income is entered in the Assets/Depreciation section. Now depending on *your* specific and explicit situation, when you get to the assets/depreciation section it's perfectly possible the property will already be entered and listed there. If it's not, then click the "Add and Asset" button and add it.