I used to be a fuels specialist and pilot for Hammonds Fuel Additives:
www.hammondscos.com
They are the only company providing fuel additive injection technology to the U.S. military in the form of JP8+100 with the 5 additives mentioned in excellent detail above, suffice to say that the method of injection is via a self proportioning flow-motive pump that in fact derives it's power via the passage of fuel through it. Additive rate thus varies with fuel rate.
If you contact the above you will receive a very warm reception from those folks and they will go out of their way to provide you with additional information.