Frag Glue

[sumpfinfishe]

You shouldn't use glue on a softie as the coral will simply let go as it secretes mucus, or worse die's from an infection brought on by the glue. Fragging softies is a bit more work than glueing a stoney coral such as LPS/SPS.
Try the method that Brad suggested, it works very well. You could also use a sharp toothpick to achor it down at the base by piercing the leather onto a small piece of rock. Another method that works well is to wrap some netting over the softie and the rock and wait a week or to for the base to attach. Frag glue or gel works best on hard stoney corals.