If all you want is a big booming bass hit with nothing else going on, EQ it so that it sounds like you want it to. The best EQ in Reason 3 is the dedicated 31-band.
If it's part of a song then that's tougher. You can separate the kick from the rest of the kit by hitting the tab key, then plugging out of drum #1's output. A balance of the EQ mentioned above first, a compressor second and an RV7000 for some ambience or a big-ass room sound depending on the tempo of the song should give you the 'booming bass hit' you're after.
Did I mention it's best to start with an 808 kick drum or low sine wav sample?