FC Document with diff Fx Rates

Dear All,

Just wanted to clear a doubt, I have created a FB60 document for  USD 1000 . The exchange rate I had taken was 62.47. Thereafter I executed Fx Valuation program by updating another rate as 64.56.

Now I want to make a partial payment of say 500 that too at different exchange rate of lets say 65.50. How do i execute F-53 ? whatever I am doing here, it is just treating everything like a normal INR document and its not even showing any line item of actual realised Loss due to this payment.

best regds

Subha