The resources register is a list of the resources supplied by the suppliers with which you do business and includes materials purchased, equipment or plant hired and labour - either external or internal. Adding or deleting from this register will not affect your data that is already entered into the cost vs. production register. Adding additional resources will make them available from the drop down selectors in the cost vs. production register.
When you add a new record in cost vs. production that has a new resource, they are automagically added to the resources register.
Fig 1: Resources Register