You can add Duty Fees in the Taxes and Charges section of the Purchase Receipt itself. If not done there, you can update add these charges by using Landed Cost Voucher.
The landed cost voucher is what I needed.
Only one thing that would be nice is to retrieve the Additional charges from an existing invoice instead of having to manually find the invoice and enter the value.
You can create a custom report based on Purchase Receipt or refer to reports like Purchase Register and Itemwise Purchase Register (in Accounts module).