I've used rid to spray shelves that I breed inverts on, and I have used it to spray bearded dragon cages in the past. Supposedly the formulation and use is similar to the stuff sold for reptiles.
In my opinion, at least if it is like the rid, it will probably not be a problem for your chameleon because any crickets that walk over the surface sprayed will die. Which is why I spray my insect shelves with it a couple times a year- it keeps the shelves free of dust mites, spiders, and ants.
I would not spray this product anywhere a chameleon might drink, however.
That said, one time I was treating a bearded dragon for mites and put newspaper down, sprayed the paper, let it dry. Later when the dragon was returned to the cage he ate some big chunks of newspaper (I don't usually use newsprint as substrate- I guess he thought it was interesting and new). He was fine short and long term- I saw no problems in him as a result of the episode. Had me worried when I saw it though.
Not that it was a good thing that it happened...
