How do I post deductions from RMD that are made to charity?

After you enter the 1099R you have to keep going.  People are stopping too soon.  

While entering your form 1099-R, if you have entered a birth date which makes you older than 70 1/2 in the tax year, TurboTax will ask you if any portion of your distribution was transferred to charity. You can then enter the amount transferred to charity.

Enter a 1099R under
Federal Taxes (Personal for Home & Business)
Wages & Income
Then scroll way down to Retirement Plans and Social Security
Then IRA, 401(k), Pension Plan Withdrawals (1099-R) – Click Start

The code in box 7 of form 1099-R must be 7 and the box IRA/SEP/SIMPLE must be checked.  A IRA QCD should be 0 taxable on 1040 line 4b and QCD written by it.  Unless you have other 1099R taxable amounts on 4b.