American Express Membership Rewards - Charges for international transaction ?

I am sending an authorization letter to AMEX - India to allow a travel agent in Bombay India to charge my credit card for issuance of a ticket. Would there be additional charges apart from ticket cost ( which I am mentioning on my auth. letter) ? I have DELTA skymiles GOLD cc.

Amex charges a 2% surcharge over the nominal exchange rate for foreign purchases. Some FTers have suggested that Amex's nominal exchange rate is a bit higher than the Interbank rate, so you may end up paying closer to a 2.5%-3% surcharge.

QL