Destroy target creature. It can't be regenerated. That creature's controller creates a 3/3 green Frog Lizard creature token.
If Rapid Hybridization resolves and the creature isn’t destroyed (perhaps because it has indestructible), its controller will still get the Frog Lizard token.
If the creature is an illegal target when Rapid Hybridization tries to resolve, it won’t resolve and none of its effects will happen. No Frog Lizard token will be created.