Add Exchange rate type to Selection Screen in BEx

BW Experts,

Business raised a request to add Exchange Rate Type(KURST) from TCURR table in the selection screen of BEx so that they can select the required rate and target currency for a particular key figure.

In Query Designer we can provide variable for currency by going into the context menu of key figure but not sure how to provide a variable on Currency Conversion Key.

Please suggest.

Thanks in advance.

-Bobby.