1. Click on the Settings gear icon, then click on Calculator Settings
2. Locate and expand the section called Customize your fixed costs and click on the + to add a custom cost
3. Enter a Name for the custom cost (e.g., padding the referral fee)
4. Enter a percent in the Amount input field (e.g., 20)
5. Using the drop-down under Type select %
6. Using the drop-down under the Multiply by select Referal Fee
7. Using the drop-down under Applies to select your desired fulfillment type FBA or FBM
8. Using the drop-down Status select On
9. Click Save, then go back to the calculator and click on the FBA or FBM fees breakdown window to see the additional fee show up.