Social Security is not on a 1099R. It is on a SSA1099. If your ONLY income is Social Security you are not required to file a tax return unless you have a 1095A for having marketplace health insurance. If you are trying to enter a SSA1099 as a 1099R you are in the wrong place.
Go to Federal> Wages & Income>>Retirement Plans and Social Security (SSA1099 and 1099RRB) to enter your SSA1099.