I experienced a similar disappointment to OP. Though contrary to what another user said in this thread - that boofing ketamine 'doesn't work', I assure you it does - I recently tried 200mg rectally last night and don't think I k-holed at all. For reference, I'm only 6'0" 140 lbs, so 200mg probably should have been enough, and I may have gotten close near the start, but ultimately failed to reach the goal. I've tested this batch before, came through clean just fine, and has worked very well the past several weekends (all rectally, doses never exceeding 100mg), but I guess it just wasn't enough to hole last night.
My concern now is why, and how to fix it - unsure if I just fucked up that particular administration (solution went into portal vessels, not systemic - syringe too deep) or if I really just need to try a bigger dose. My only concern with the latter is that a larger dose - say, 300mg - runs the risk of just knocking me out and then I don't get to experience any of the trip. Is it worth upping the dosage by a significant amount, or just be more careful with ROA next time? Could also try a little bit of weed in there to help amplify the effects I suppose, but was curious as to whether anyone has an opinion on what may have happened given the mg/lb ratio