FWIW, I've made a few 1-hour connections from US to Schengen at AMS - you just have to show the agents at the immigration line that you have a flight departing shortly, and they'll point you to the quick connect line.
I wouldn't exactly recommend it, as you have no margin for error (one time, my flight was 20 minutes late arriving into AMS, and I RAN from the outer reaches of D, through immigration, and to the end of the B concourse for my next flight, but I still made the 40 min connection), but it is doable.
Also, I'm not sure how many AMS-OTP flights KL has per day, but if you book through DL, DL reservations will be happy to protect you on the next KL flight if it looks like you won't make your connection before you leave the US. It's happened to me a few times, and they've made the change on the KL connecting flight without skipping a beat.