Game says use [Use]. Check Controls menu. It says Use=Ctrl. So you use [Ctrl] to [Use]. Also, while you're at it, you can consult the rest of the controls. It would be better if all the in game art changed depending on what the controls are binded to but if it's too complicated, too time consuming (and therefore too costly) then whatever. They're not the first game to do it and they won't be the last. Imagine most PC gamers consult the controls anyway. It's really not that big a deal.
Although maybe you guys should in case Matthewmatosis turns his ire towards it