If you're going to use clusters to monitor which targets to cast it on instead, you'd go under Options-General-Clusters, you'd adjust the range to 10, health level to whatever you want (I put it at 95%), Operation Mode-Radial. Max number of heal targets is up to you. You can slide it all the way to the right cause technically it doesn't have a cap on how many ppl it hits but its effectiveness severely decreases past 6 targets so you might want to set this to 6 instead.
Set the cone to 360, source to Target, destination to Raid and if you want a counter displayer, check it and set it to what you want to be fair and good values. Then go to Options-Panels-Hots and choose Cluster Finder for one of the hot slots.
Keep in mind, you gotta try this out in an area with map coordinates (lots of fights in DS don't have them), with some grouped ppl (the more the better), and they gotta be below the health threshold you specified in clusters options.