Manek, who has visited Oklahoma seven times already, was scheduled to take an unofficial to Norman this weekend.
"I've always been a Boomer Sooner fan," Manek said. "The coaches are great, and it just felt like a great fit."
The 6-foot-7 wing helped lead Harrah to a berth in the Class 4A state semifinals last year. He averaged around 15 points per game as a sophomore.