Manually Set Resolution

In Game for Killing Floor and Red Orchestra 2
Drop down the games console with the "`" button on your keyboard and type the following: setrez xy
Where x and y are the resolution you would like it to display.

Editing Killing Floor .inis

Open up your KillingFloor.ini in your killingfloor system folder and look for the following lines:
ResX=
ResY=
And change them to what you would like the resolution to be.


Editing Red Orchestra 2 .inis

Navigate to your Documents/ My Games/ RedOrchestra2/ ROGame/ Config location and open the ROEngine.ini and look for the following lines:
ResX=
ResY=
And change them to what you would like the resolution to be.