I can't seem to find it. Quicksave works great, but Quickload of lack thereof is somewhat troubling me. I tried all the Function Keys, and no one seems to work. It says in the manual that there is, in fact, a Quickload button, so I must be blind, crazy or both.
 

1.4 Saving and loading the game

The game will automatically make a savegame from time to time at important points.
You should also save the game yourself in the moments you deem appropriate.
The F5 key serves that purpose. You can load a saved game by selecting the „Load
game” option in the menu, where you will find a list of saved games. When in game,
you can use the quickload key to load the most recent savegame.

Weird, it's usually F8 or F9. I've never needed to quickload though, so I can see why they might have left it out (though they should have included it for people who wanted it). 

I could never find a quickload; while I never needed one per se, I decided I wanted to actually stealth, the stealth bits and a quickload would have made that easier in places.