In your <RatingBar>
use:
android:numStars
to define how many red_circle
are used for the full scale of the bar.
android:rating
to set the default rating level.
android:stepSize
to define the step size of your RatingBar.
<Edit>
I don't believe RatingBar is designed to work using a straight fill color as the progress drawable, which is what you have currently. A color has no dimensions, so drawing 2, 3 or 4 of them has no meaning.
It is designed to work with an image file like the default star png files.
Change your layer-list so the progress drawable points to a Bitmap, or 9Patch, and it works fine. <RatingBar>
extends ProgressBar, which uses 9Patchs for the progress drawable.