A good example of using a Fixed Limit Per Price scheduling option and at the same time assigning a Resource to a Session, would be when you want to limit the amount of children that can go out on a tour on any given day.
Firstly within a Product's Scheduling tab, set the limits accordingly (click here for further information):
during the creation of the Session for this Product, you'll have:
1. the option to assign a Resource, in this case the Bus
2. confirming or adjusting the limits for each price option
So now when an Order comes in for 3 Adults and 10 Children, not only are 13 spots taken on the Bus Resource, but also Child seats are no longer available