Knowles touched on his defensive system, reasons for coming to Penn State, and drive to win a national championship.
Tinsley spent 2024 on the Washington Commanders' practice squad.
Smith served as Penn State's offensive analyst and analytics coordinator for the last two seasons.
Mills will attend his third school after attending Lackawanna Community College before Penn State.
Barkley, along with three other Penn Staters are set to represent the Nittany Lions in this year's Super Bowl.
According to FootballScoop, Penn State offered Knowles $3.2 million a year.