How can the rate for an Inventory Item be populated in projects budget screen using planning RBS

Summary:

How can the rate for an Inventory Item be populated(rate direct from inventory) in projects budget screen using planning RBS.

I am trying to create a cost budget for a project using the planning resource breakdown structure, resources and Job rates are fine which is populating from rate schedules assigned but while selecting an inventory item the item rates are not auto populating.

Resource class structure is defined for 1)Exp Cat 2) Exp Type 3) Named Resources 4) Inventory Item: Oraganization 5) Job and Exp types and Inventoty items assigned.

How can I bring item cost rate from Inventory module or is there any config that I need to?