The indication that the $5,000 was transferred to charity is made during the entry of the Form 1099-R.
You must be age 70½ or over at the time of the distribution. However, for those with a birthdate between July 1, 1949 and June 30, 1950, 2020 TurboTax presently (now version R16.1) has a bug the prevents it from asking the necessary question regard transfer of the distribution to charity. See the workaround described by macuser_22 above.
