You can use "CR" to separate lines of buttons.
BR breaks the line, and moves the next icon down and to the left.

Consider this image (it's kind of old, but works):

I have 2 rows
1. Healing Wave, Lesser Healing Wave, Chain Heal
2. Tidal Force, Cleanse Spirit, Riptide

The profile looks something like this:
n,raid,gRaid1
n,raid,CR
n,raid,gRaid2

The groups look like this:
gRaid1,SB_HealingWave,*
gRaid1,SB_LesserHealing Wave,*
gRaid1,SB_ChainHeal,*

gRaid2,SB_TidalForce,player
gRaid2,SB_CleanseSpirit,*
gRaid2,SB_Riptide,*