~50mg smoked [harmine/harmaline freebase] is enough to double the length of a DMT blast (hypothetically, of course).
Oral doses of ~100 mg are probably sufficient to achieve facilitation via MAO inhibition, but you might wanna shoot closer to ~200mg to be safe. Purging is less likely with this extract than with straight up rue or rue brews, but it's still possible of course, due to the nature of the medicine itself.
Speaking of which, DO NOT mix harmaloids with psychoactives that increase the amount of serotonin active in the brain, like SSRI's (certain perscription psychoactives for depression or anxiety such as Paxil, Prozac, Zoloft, Lexapro, et al.) or for up to 8 weeks after stopping the SSRI (at least in the case of Prozac, which lingers like a mofo... the others should be gone in 4-6 wks but better safe than sorry!) Too much serotonin can lead to serotonin syndrome, which can in turn lead to death from hyperthermia. Also avoid MDMA (ecstasy) which also increases 5ht amts in the synapse. Also avoid nasal decongestants, allergy medications, amphetamines, antihistamines, or anything else which can cause hypertension, or hypOtension ...snip...