use '?' for JOKER (blank)

From letters P, R, O, P, O, R, T, I, O, N, A, T, I, N, G  I made following words

15 letter words

proportionating[20]

13 letter words

proportioning[18]

12 letter words

apportioning[17]

11 letter words

propitiator[15], prorogation[14], protonating[14], protonation[13]

10 letter words

appointing[15], proportion[14], portioning[13], antiproton[12], originator[11], rattooning[11]

9 letter words

propining[14], proponing[14], appointor[13], apportion[13], optioning[12], pronating[12], parroting[12], prorating[12], pronation[11], proration[11], partition[11], arointing[10], rationing[10], ratooning[10], intrigant[10], nitrating[10], attorning[10], intorting[10], nitration[9]

8 letter words

trapping[13], tripping[13], agitprop[13], pinpoint[12], aproning[11], painting[11], patining[11], opiating[11], poignant[11], pointing[11], poontang[11], pirating[11], printing[11], trooping[11], antiporn[10], troponin[10], pronator[10], potation[10], portrait[10], training[9], rigatoni[9], ignorant[9], ignitron[9], rogation[9], tainting[9], notating[9], attiring[9], rotating[9], oratorio[8], notation[8], antiriot[8], rotation[8], irritant[8], nitrator[8]

7 letter words

napping[12], nipping[12], pogonip[12], pooping[12], rapping[12], ripping[12], tapping[12], tipping[12], topping[12], rappini[11], propria[11], appoint[11], rapport[11], paining[10], opining[10], pogonia[10], pairing[10], pignora[10], parring[10], panting[10], parting[10], prating[10], porting[10], patting[10], pitting[10], potting[10], opinion[9], nonpoor[9], pintano[9], pontoon[9], atropin[9], patroon[9], pronota[9], portion[9], airport[9], antipot[9], triptan[9], patriot[9], taproot[9], tripart[9], oogonia[8], ingrain[8], raining[8], ironing[8], organon[8], roaring[8], atoning[8], airting[8], ranting[8], trining[8], orating[8], ignitor[8], rioting[8], rooting[8], tarring[8], grantor[8], tinting[8], toiting[8], tooting[8], ratting[8], tarting[8], rotting[8], oration[7], intrant[7], introit[7], arnotto[7], rattoon[7], tortoni[7], traitor[7], rotator[7]

6 letter words

piping[11], priapi[10], riprap[10], pinang[9], pining[9], pooing[9], paring[9], raping[9], riping[9], pirogi[9], poring[9], roping[9], taping[9], opting[9], toping[9], ragtop[9], panini[8], panino[8], pinion[8], rapini[8], nonpar[8], option[8], potion[8], ponton[8], parton[8], patron[8], tarpon[8], tropin[8], pronto[8], proton[8], parrot[8], raptor[8], torpor[8], gonion[7], airing[7], oaring[7], onagri[7], origan[7], origin[7], raring[7], garron[7], anting[7], tining[7], gitano[7], noting[7], toning[7], gratin[7], rating[7], taring[7], tiring[7], trigon[7], agorot[7], trogon[7], ronion[6], anoint[6], nation[6], notion[6], aroint[6], ration[6], natron[6], nonart[6], intron[6], ratoon[6], orator[6]