PKF file extension stands for Peak File, the PKF are created in adobe audition. Adobe Audition is an audio production file. The file contains waveform of data that is automatically generated when an audio file is opened or imported. 

Silky Terrier Dog Breed Playing Aro... Silky Terrier Dog Breed Playing Around
The PKF file can be run on both Mac and windows through Adobe Audition CS6 software. Silky Terrier Dog Breed Playing Around