You should receive a Form 1099-R that is used to report all of your retirement distributions you received during the year. This form(s) will need to be entered into TurboTax when you prepare your tax return. As you enter your information, TurboTax will ask you questions about the required minimum distributions (RMD). Be sure to read each question carefully to ensure you report your RMD.
Follow the instructions here to enter your 1099-R into your tax return.
After you enter all of your information, you will see the following screens which will prompt you to enter the amount of the RMD you received during the year.