In this particular case centripetal force is the reaction of the circular surface.
Comment: thanks for reply. So, where is the centripetal force(seeking centre for rotation) in this case to cause circular motion? or, which one is the centripetal force in this particular case?
Appreciate your clarification.
Well, centripetal force is more general name. Centripetal force is a force "seeking" center of rotation. In our answer we've considered specific case - motion on the circular surface, but there could be also, say,& motion on the rope.
Comment: We were told that force F shown is Centripetal force while you called it normal reaction of the surface of circle. Kindly advise.