Quarterback Nate Montana isn’t on the 49ers’ 90-man roster, but he’s been a regular visitor to the team’s facility over the past six weeks. On Friday, the son of the 49ers’ Hall-of-Fame quarterback attended a one-day rookie minicamp in Santa Clara, marking at least the third time he’s thrown in front of San Francisco’s coaches since he attended a pre-draft local pro day April 17. Montana also attended the 49ers’ rookie minicamp on a tryout basis from May 10-12. On Friday, Montana was an invitee to the one-day camp, which included the rookies on San Francisco’s 90-man roster. The camp was part of the NFL’s seven-week “Rookie Football Development Program.” Under the guidelines of the CBA, such rookie camps can be held on weekdays during a seven-week period, which begins in mid-May. Other invitees to Friday’s camp included former Sacramento State middle linebacker Jeff Badger and UC Davis linebacker Jordan Glass.