I understand your frustration.
The current rating system is less than ideal. Currently you need to rate one track at a time, and must leave a comment. And press the rate button individually for each track.
HOWEVER, we are almost done updating the rating process, and it will be extremely easy and user friendly to rate in the VERY near future. It could be any day now that the update is complete.
If you can be patient for a short while longer you will not be disappointed.
I apologize for your inconvienience.