Hi Arminder,
Mere adding authorization objects to roles will not help system understand what to restrict. Ultimately it is a program logic which system understands. So the logic should be available to achieve the function.
For your requirement you can do following as PR creation is not possible to restrict on cost center through standard code.
- Check if there is user exit to insert check on cost center using standard auth object or custom auth object.
- Create custom transaction as copy of standard PR creation transaction and insert a check to restrict access based on cost center.
BR,
Mangesh