What are the setups to enable the front and back loaded spread curve functionality

What are the setups to enable the front and back loaded spread curves for the purpose of allocating the budgeted and forecasted amounts in oracle fusion?

Following setups were checked to enable the allocation of the amounts using the above mentioned spread curves, however the allocation is being allocated on the basis of spread even spread curve:

Manage Resource classes: Spread curve-Resource class Labor was assigned with the Front loaded spread curve and the respective project unit and expenditure type were selected.