Atop rhymes with:
nonstop, stop, top, topp, bop, bopp, chop, chopp, cop, copp, crop, cropp, dopp, drop, flop, glop, gropp, hop, hopp, hoppe, jopp, klopp, knop, knopp, kopp, koppe, kropp, lop, lopp, mop, nonstop, op, opp, paap, paape, plop, pop, popp, poppe, prop, propp, raap, ropp, schaap, schopp, schoppe, schropp, shop, shoppe, skop, slop, sop, sopp, stop, swap, swapp, top, topp, tropp, tschopp, wop, yopp
Atop sounds like:
additive, adobe, advo, atp, attaboy, audiotape