Undrafted rookie S Anthony Perkins has signed with the Broncos, according to his agent, David Canter, who tweeted the news Saturday afternoon.

Perkins worked with the Broncos during their rookie camp in May as a nonroster invitee but wasn't offered a contract after three days of work.

The addition of Perkins comes in the wake of S Quinton Carter's hamstring injury, which he suffered when he tumbled to the ground Friday after being beaten by WR Eric Decker for a touchdown.  Carter's injury won't require surgery, coach John Fox said. But the Broncos are expected to be cautious to avoid aggravating the injury.

"I don't like putting a time frame on it, but it is a hamstring injury," Fox said.

The Broncos only had five healthy safeties for Saturday's practice, forcing Rafael Bush to handle double duty on the second and third teams.  Carter worked on the second unit Thursday and the first team Friday before being injured.

Denver doesn't have to cut anybody to add Perkins because it was two players below the roster limit after letting go of injured rookies Eric Page (ACL tear) and Coryell Judie (disc) on July 25.

For up-to-the-minute Broncos updates, follow Andrew Mason on Twitter at @CBSSportsNFLDEN and @MaxBroncos.