The Steelers signed Rader to the active roster Tuesday, Teresa Varley of the team's official site reports.
Rader entered the league as an undrafted free agent in 2018 and has yet to make his NFL debut. He could get a chance this week against the Ravens following news that tight end Zach Gentry was placed on injured reserve with a left knee sprain. However, Vance McDonald (illness) could return to the lineup, which may put Rader in healthy scratch territory.