Originally Posted by
Ditto
Any fees that KLM charge will be clearly visible in the payment screen... after you've entered the first 6 digits of your credit card.
If they require surcharge with your card, I suppose you can just use PayPal instead (Although not with Amex)

I did enter the first 6 digits of my MasterCard, but it shows "invalid number" as the result. I guess their system doesn't recognize card number issued in USA.