Apportioning rhymes with:
airconditioning, auctioning, auditioning, captioning, cautioning, commissioning, conditioning, cushioning, decommissioning, fashioning, freshening, functioning, malfunctioning, mentioning, motioning, optioning, partitioning, petitioning, positioning, rationing, reconditioning, repositioning, sanctioning, sectioning, stationing, transitioning, vacationing
Apportioning sounds like:
aberrations, aborting, abortions, affording, apparitions, averting