Here's what rhymes with riverflow.
low flow slow throw row lo fro ro thro yo floe roe yeux rho throe sloe no so know go though show co blow grow snow pro tho fo foe glow ho overthrow bo doe dough mo overflow po toe wo woe crow hello tow beau ceux faut goe hoe jo ko sew soe vo aglow beaux cho dau mow noe sho zo bro stow trow whoa doh schmo schmoe although below ago quo chateau folio bio forego forgo tableau uno escrow siglo tableaux tuo chateaux chapeau oleo tarot deathblow foreknow overgrow kayo chapeaux borzoi resew ratio radio plateau audio bestow buffalo stereo nouveau polio propos vertigo aliquot dicho mistletoe outgrow rodeo topos afterglow dunno plateaux trousseau adagio kapok piccolo turbot regrow gateau fatso gateaux pekoe trousseaux romeo embryo studio indigo patio calico apropos cameo presidio spatio oregano bandeau matzoh tallyho undergo portico bungalow dynamo domino medico pistachio undertow mustachio microdot moustachio portfolio politico impresario braggadocio pompano archipelago pianissimo generalissimo