Which gst to charge

we are manufacturers of Pharma machine in maharashtra, we have recieved a order from madhya pardesh, he is a merchant exporter. so once the goods ready he will arrange his own transport, collect and dispatch the goods through nhava seva port in maharashtra to Saudi ,
please advise what to charge
cgst sgst or igst
further since the order is under confirmation stage is there any documents we have to take from him as of now since we will be charging him gst @ 0.10%.
post shipment he will provide us export documents within 90 days