Form 1099-K, like all 1099 Forms, is an information return. If you are already reporting the amount shown on the Form 1099-K as taxable income on your return, you don't need to do anything else.
(There isn't a place to enter Form 1099-K on your tax return. You just need to account for it elsewhere, usually as "General Income" in the Business Income interview of TurboTax Self-Employed).
