I don't know about everybody vibrating at a different frequency. Nor would I know how that could be measured?
The theory behind frequencies killing pathogens is similar to how the human voice can shatter a glass. Nearly all sounds that come from the mouth of a human will not harm that glass. But if you sing at precisely the right note it creates a vibration that shatters the class.
So, theoretically, it's the same with rife frequencies. If you find the exact right frequency you can shatter various bacteria, viruses, and other pathogens. unfortunately, this creates a Herxheimer reaction as you must now deal with the dead pathogens.