If you made a regular distribution in 2017 (code J, T or Q in box 7 of the 2017 Form 1099-R, yes, on your 2018 tax return it only potentially affects your Retirement Savings Contributions Credit.
(Of course the 2017 Roth IRA distribution also reduced your contribution basis in Roth IRAs, so it potentially affects whether any subsequent distributions from your Roth IRAs are taxable, but that has nothing to do with the entry you make in the Retirement Savings Contributions Credit section.)
