No, you are not supposed to smoke this. Just bomb (fill it into a cigarette paper or capsule) it as you would do with a pill. Other possibility would be dissolving it in water, or - if you like bad taste - just swallow it, as it is :D.
Dosage -> check literature. 75mg - 100mg would be an average dose, 100 - 150 if you are experienced/know that you need a bit more. If I remember right the rule was 1.5mg / kg, but I am not sure, better check yourself/wait for confirmation!
All assuming that it is 'clean' (where you got the 90% purity from? the good old dealer who gets it directly from the lab?

), if it is could you need more, ofc. But taking this material for the first time, you should be careful - Marquis can just give a qualitative result, if you used it.
If you don't have a scale, there was a thread recently that dealt with this topic.
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