What value is to be mentioned in export invoices?

We provided a service to an American company and issued an invoice under LUT. The invoice was issued in US dollars. The amount we received was minus a lot of charges. When we mention the invoice in GSTR-1, what INR value do we have to mention? Do we mention the actual amount we received in Indian rupees? Or do we have to use some form of exchange rate on the dollar amount on the invoice?

For example if the invoice was of $1000, and we received Rs 69,000 after deduction of all charges, do we mention Rs 69,000 in the GSTR-1 or do we have to use some exchange rate of USD to INR? If if we have to use an exchange rate, which one?

Also, is it required to mentioned in IFF or directly in GSTR-1?

Thanks in advance for you help.