Rivers signed a contract with the Seahawks on Wednesday, John Boyle of the team's official site reports.
The 23-year-old running back is slated to add depth for Seattle, after the team placed linebacker Jon Rhattigan on the reserve/physically unable to perform list Wednesday. Rivers signed with the Cardinals back in May but was waived earlier this month. With just days before the Seahawks kick off their preseason finale Friday against the Cowboys, there's uncertainty if the rookie will suit up given the short turnaround. Among Rivers' competition for a roster spot in the team's backfield is Josh Johnson and Darwin Thompson.