Hi Kabil,
Try,
AT PAI.
LOOP AT IT_VENDOR.
CHAIN.
FIELD WA_VENDOR-VENDOR MODULE Vendorname ON CHAIN-REQUEST.
FIELD WA_VENDOR-NAME1.
FIELD WA_VENDOR-GSBER.
FIELD WA_VENDOR-DMBTR MODULE CALC." on CHAIN-reQUEST.
MODULE TBC_100_MODIFY ON CHAIN-REQUEST.
endchain.
FIELD WA_VENDOR-SEL
MODULE TBC_100_MARK ON REQUEST.
ENDLOOP.
MODULE TBC_100_MARK INPUT.
" Add logic to insert the line in internal table.
ENDMODULE.
Hope it helpful,
Regards,
Venkat.