McGill is head coach Steve Masiello's first pledge in the Class of 2015.
"I like the coaching staff, I like the style that they play," McGill Jr. told SNY.tv. "They play an uptempo game. I felt like it was the best fit for me out of all the schools.
"My heart gave me a feeling to commit now [for 2015] rather than later."
He also considered La Salle and Iona, among others
"Rickey is an extremely quick guard with a huge motor," his AAU coach with House of Sports, Andy Borman, told SNY.tv.
"He can really defend and score in both the halfcourt and transition. He went toe-to-toe with Kaleb Joseph (Syracuse) and Paul Jorgensen (GW) this summer and scored 25+ against both players.
"He is a great get for Manhattan and if he continues to work on his game he can play for them on day one. The kid could play in the bottom half of some high-major conferences."
Manhattan has four pledges in the Class of 2014 in Samson Akilo, Samson Usilo, Calvin Crawford and Zane Waterman.
Manhattan was the preseason No. 1 pick in the MAAC this year.