What's the best vape pen for use with Rick Simpson Oil (RSO)?

Rick simpson oil is very thick oil, it is not fluid enough to use in a vape pen. I have tried it myself with a vape pen that was supposed to be able to vape thick oils with no luck. I have also tried thinning the RSO oil down with vegetable glycerine but it separates from the RSO. Maybe someone else can chime in on this topic, would love to hear the answer!