Breakaway cable hook up

When I purchased my RPOD the owner showed me how he connected the breakaway cable.  He had it attached to the safety chain hook.  I got to thinking about this and don't think it would work that way.  I suspect it needs to be hooked to the hitch independant of the safety chain. I would think you would want it slightly tighter than the safety chain so if it came unhooked it would put the activate the breaks.  Is that correct?  I am thinking I need to get a hook so I can attach it easily.

I use a D hook and attach it to the area where you would attach the safety chain S hook to the tow vehicle. Do not attack the break away to the chain itself, and make sure the break away cable is not to long either. It should be shorter than the chain that way it will break away, is it is longer than the chains it may not break away due to the chains being longer than the cable.