How to add post rating on blogger?

While I was trying to learn how to run php code on blogger, I found this post

http://www.mybloggerlab.com/2014/02/how-to-add-post-rating-system-in-blogger.html

Thought of trying it.

1. Go to http://rating-widget.com/get/rating/blogger/#editor

2. Press signup & add to blogger

3. You can either press Add to blogger
or show source code.

4. I did Add to blogger and it just worked. After all my posts i see five stars to be rated

5.  I want to verify if it works on mobiles too.

6. Another thing I want to check is if, the ratings can be seen only by me or by my readers too

7. Last thing I want to check is that it shouldn't make my blog slow.