An SFK file stores the waveform image of an audio wave (.WAV) file saved by Sound Forge Pro, MAGIX VEGAS, or a Sony digital media device. It is created automatically when an audio file is opened with Sound Forge Pro or Vegas. SFK files are stored in the same folder with the same name as the audio file, but with ".sfk" added after the original extension.

SFK files are used by Sound Forge Pro and MAGIX VEGAS to visually represent audio data, but are not meant to be opened or edited manually. SFK files do not contain any actual audio data. If the related audio file is modified in a different program, you can regenerate the peak file by selecting "Rebuild Peak Data" from the Special menu in Sound Forge. NOTE: Sound Forge Pro was previously developed by Sonic Foundry, which was acquired by Sony in May, 2003, then Sound Forge Pro was acquired by MAGIX in 2016.