File to RFC PI 7.1

Hii..Currently iam working in File to RFC Scenario.In message mapping i have to write some logic....My problem is

In my source mapping i have my company id..but in my target message mapping ( RFC message RFC_READ_TABLE)..

What i need to do is i want to reterive data according to source company id using this functional module...How to map source

and destination...

With Regards..

Dinesh