Railroad Retirement income is reported on a Form RRB-1099-R. If you haven't received your RRB-1099-R, you need to wait until you receive your RRB-1099-R before you e-file.
The IRS requires plan administrators to put your Form RRB-1099-R in the mail by January 31st. If you lost your Form RRB-1099-R, ask your local RRB field office for a new copy or go to rrb.gov to request a copy.