I use Rhizo all the time, think it's the best root stimulator out there and have frankly lost my fear of using it or even being super careful about measuring it during a grow. Somewhere here on RIU I read that somebody was soaking seeds in it and somebody else was adding it to paper towels when germinating....so I finally gave in and gave it a try. My results were not too awesome....I tried the following experiment;
1 seed soaked in Rhizo water for 24hrs then dropped into paper towels then placed in a rapid rooter.
2 seeds soaked in plain water 24 hours, germed in paper towels then placed in rapid rooter soaked with Rhizo water.
3 seeds stuffed straight into rapid rooter (Subcool method) with plain RO water to moisten.
Results; anything to do with Rhizo during seed pre-soak or rapid rooter pre-soak brought up seedlings fast but either had problems dropping the seed hull, or a skin from the inside of the hull captivated the cotyledons and kept them from opening up. All three sprouts with issues showed the same trait with the cotyledons....they remained curled over to one side, unable to spread leaflets and absorb light. They exibit a "reddish" colored band around the stems. The three seeds jammed into plain watered rapid rooters, popped up, spread cotyledons and started looking healthy. I was able to take an exact-o knife and fine tipped tweezers under a scope and surgically remove the "hull liner" that entrapped the sprouts with issues. They are growing but looking a little "stunted". Kind'a looks like the one Rhizo soaked seed popped a tap root during soak faster than ever in my history, but the end result was the same....a membrane from inside the hull couldn't be shed once above ground. Anyhow, whether this was a controlled experiment or not I might just stick with the old "Subcool" germ standard. BTW, not 24 hours after all 6 were up and opened they all got some Rhizo and Canna "Start"...no ill effects there or since then.