Well not having the reputation to comment, and seeing that this is SQL Server could you do the following?:
SELECT st.*
, dbo.ufn_usage_and_consumption(st.item_number, st.lot_number)
from some_table st
Basically, you are calling both the view and FOR EACH ROW of the view, calling the SQL Server Function.
Please note that this is NOT OPTIMAL. You are essentially doing RBAR processing (Row by Agonizing Row) and calling the function for every row.
Really, I would see about creating a stored procedure, if your report writer supports that and pass parameters to call the query and pass results back.
I'm making the following assumption: 1) the data coming back from the function is a scalar (one value only), if it's not you can return it as a comma delimitted string
Don't know if that helps or not but good luck with your query!