Do the rates always post on the first of the month in your secondary data source? Or can they sometime change mid-month?
Try creating these two calcs
In the primary:
DATEPART('month', [Receipt Date] )
In the secondary:
DATEPART('month', [R-DATE] )
Then add the edit relationship to link on these two. This will give you the rates.
Hello Shawn and thanks for responding. The rates can change at any time. Also, I will update the wording to clarify that my goal is to multiply the quantity measure by the corresponding rate for each transaction.