Unrestricted free agent defensive back Keiwan Ratliff has agreed to a one-year contract with the Pittsburgh Steelers, according to a league source. Ratliff recorded 32 tackles and two interceptions last season in four starts for the Indianapolis Colts. The former University of Florida standout has registered 136 career tackles and five interceptions during his stints with the Colts, Tampa Bay Buccaneers and the Cincinnati Bengals.