While Botox for masseter reduction will certainly taper and slim your jawline, it will be orders of magnitude less significant than the photo you have morphed. With serial treatments especially the masseter muscle will atrophy and become very slim, but ultimately your result will be...
If you still see the frown lines following your Botox treatment, either you need additional Botox injected or you need to have it placed slightly more lateral (closer to eyebrows) to stop those muscles from squeezing. I hope you find this helpful.
This is not an uncommon problem when the injection method used is the classical method developed in Korea. There is a different method leaving out the injection areas closest to the mouth and that allows you to be able to smile while still getting the tapering effect. As for now, give it some...