IME the best way to read the kit is to toss it in the garbage and get a SeaChem kit or Salifert, sorry... IME they are junk and wonder how they can keep making such a kit.
When I first got the RS kit I almost overflowed the vial trying to get a color shift, no such luck, I was pushing a 3000ppm reading before I gave up.
For simplicity I like the Salifert kit, for accuracy the SeaChem is a great kit.