There is only one file type that uses the .KF2 extension:
Max Payne Resource File
Game resource file used by Max Payne, a violent, third-person shooter noir video game; contains weapon models, projectiles, skyboxes and keyframe animations.
The Max Payne game uses several file formats to create the different aspects of the game environment. The KF2 is the most widely used format, along with, .KFS and .SKD files. These files are found within the .RAS archive file.
Updated: May 22, 2014