How to add a parameter which is a formula

We have a formula to get the sales rep (called the corrections rep) and would like to offer this a param if the user only want to see and process their own

records. how to make this as a param?

this is the formula

(

SELECT

    {fn REPLACE(MYDTA.REFER1.RFDTA,'0000000' ,'' )}

FROM

    MYDTA.REFER1

WHERE

        MYDTA.REFER1.RFCAT = '0025'

    AND MYDTA.REFER1.RFSQ2 = '1'

    AND MYDTA.REFER1.RFSLC = "OEORH41CD"."OHSLR#"

)