Watts Quick Connect / John Guest style fittings... proper installation?

I just need to make the final connections on my Reverse Osmosis system. Kit I purchased included John Guest type quick connect fittings for the plastic tubing (polyethylene). The tubing that was supplied is color coded and seems to be little stiffer (holds it shape better) than the translucent clear tubing that you find at the hardware store. When I've made compression connections in the past, I always used the brass or plastic anti-crush tubing inserts. Do I need to use them or is it a problem if I use the with the quick connect type fittings?

Thanks..

John Guest fittings do not use the ferrule, at least not on the smaller sizes.

Thanks... installed without the inserts and so far no drips....