The concept of flow types allows you to define other flows - such as charges or commissions (absolute or proportional) - for the individual product types. These other flows are created with each transaction.

The prerequisite for this is that you have maintained the flow types in Customizing and assigned them to the flow category, "Other flows/conditions". You must have also assigned these flows to the required product type/transaction type combination.

You see these flow types as a proposal here in the area, Other flows. You also still enter the payment amount, currency with the direction and the payment date.