I'm retired and this is my 1st year or doing an RMD. I'd like to have an estimate of my Fed tax based on my RMD and SSA. Can I do that now with Turbo Tax?

You can use Forms mode, click on Forms in the upper right of the desktop program screen when using Windows.  In Forms mode click on Open Form.  Type in 1099-R.  Click on the result to open the form.  Enter the amount of distribution, taxable distribution, tax withheld and in box 7 enter a code 7.

To enter Social Security benefits reported on form SSA-1099

Click on Federal Taxes (Personal using Home and Business)
Click on Wages and Income (Personal Income using Home and Business)
Click on I'll choose what I work on (if shown)
Scroll down to Retirement Plans and Social Security
On Social Security (SSA-1099, RRB-1099), click the start or update button

Or enter ssa-1099 in the Search box located in the upper right of the program screen. Click on Jump to ssa-1099