Charge Calculation Freight Agreement

Hello,

At the end of the transportation the carrier can send additional kilometer information that was needed that reach the customer in the fastest way. We need to have a predefined value like 1 euro for each additional kilometer, so that the TM users only has to fill manual the additional kilometers. How can I set a predefined value for each kilometer? What is the best way to set this up? In case of a manual charge type I'm not able to set a predefined value of 1 euro. In case I use a Rate Table the correct Scale and Calculation Base is missing.

Any help is welcome!

Regards,

René