Humble Bundle Weekly: Are german keys clearly marked as such?

Nope. There's no indicator of what you're getting at all. German keys are indistinguishable from other keys.

The titles are just, well, normal ("Red Orchestra 2 Steam Key") and even the keytypes don't give it away if you dig into the front end ("tripwire\_weekly\_redorchestra2steam")

Cannot say for Killing Floor since I already owned it before but here is a scan of how it looks like for Red Orchestra:
http://i.imgur.com/M0mVbAN.jpg

i bought and activated ro 2 and kf from bundle recently having german ip... Will check

The key itself look like every other key. If humble declared them this time as DE I don't know. However,if you activate them,then you will see,although it's also too late then.

Okay guys, thanks for the quick replies! Too bad it's not marked in the first place.