where do i capture or record costs for "free form, project" contract line for the Contract

Summary:

Hi Team,

where do i capture or record costs for free form project contract line in Contracts, As i see Invoice Amount and Revenue Generated for the Contract lines in Financial Summary tab in Contract Header and "Summary Revenue" task in Contracts Revenue.

I want to track the profit and margin for the Contract line which i billed to customer.

Business usecase:-

As we are Delivering services on behalf of Installation of equipment or FMS services, we want to capture the cost that is incurred for our org and also analyse margin w.r.t to the cost , invoice amount and revenue recognized for the respective Customers.