GST REFUND ON EXPORTS:

Mam,  my client has made exprte without paymentof tax.  He would have file rfd01 for claiming  the accumulated itc. He hasn’t shipping bill no as shipping bill is not required if shipping bill is less than prescribed kg. How to apply for GST REFUND ON EXPORTS in this case.
What  should we do  as shipping bill n egm no. Is compulsory field in filing of  rfd01
Plz help me