They need an atomizer that allows for bottom feeding (i.e. has a hole in the bottom of the connection). You press (squonk, as we often refer to it) the bottle, and
juice flows up a tube into the atomizer to wet the wick. You need to press the bottle every few puffs. It quickly becomes second nature. I've been an exclusive REO user for over 4 years, and started out using 306 and 510 atties, then cartomizers, then
rba's. REO sells several compatible RBA's, and many others are available or can be modified to allow bottom feeding.