How to modify field catalog of a copied standard report program 'RFIDYYWT'.?

Hi All,

I have made a Z copy of standard report program 'RFIDYYWT'.

I need to modify the output of this program by adding a field to display

'Clearing document number' for all the vendor line items already paid.

Please let me know how to modify the field catalog of this program so

that I can add a new column at line item level ?

Thanks and Regards,

Tejaswini