Go to Federal> Wages & Income>>Retirement Plans and Social Security (SSA1099 and 1099RRB) to enter your SSA1099.
When you enter your SSA1099 you will be able to enter the federal tax withheld from your benefits in box 6,
When you enter your social security benefits there is a box for federal withholding.
If you have state withholding you must enter it using the steps below.
This will allow state additional withholding not entered in any other location.