You can find that functionality in some of the online demos...
The occupied timeslot demo shows how to limit appointments per time slot, which also lets you up the number of appointments allowed in a timeslot by increasing the AppointmentsLimit constant:
As far as time slots go, they are fully configurable, check out this demo which shows the range of options you can use for defining your timeslots:
So in short, yes you can do this with Telerik RadScheduler. :)