Not a form just for recording cost basis. All of the worksheets and forms are used to compute the depreciation on the property, so the cost basis must be entered. In TurboTax, the forms that are created when you enter your new rental property that show the basis of the property are:
Asset Worksheet (not filed with the IRS)
Depreciation and Amortization Report (not filed with the IRS)
New Rental Property Worksheet (not filed with the IRS)
Form 4562, Depreciation and Amortization (filed with the IRS).