Adding Margin / Padding to RatingBar

I have an image of a rating bar:

Now, I would like to know how to add a field / padding to each item in the evaluation bar?

styles.xml

<resources>
<style name="starRatingBar" parent="@android:style/Widget.RatingBar">
    <item name="android:progressDrawable">@layout/starratingbar_full</item>
    <item name="android:minHeight">19dp</item>
    <item name="android:maxHeight">19dp</item>
</style>
</resources>

      

        
        
        
      

    

starratingbar_full.xml

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_height="20dp"
android:layout_width="30dp">

<item android:id="@+android:id/background"
    android:drawable="@drawable/starunselected"
    />
<item android:id="@+android:id/secondaryProgress"
    android:drawable="@drawable/starunselected" />
<item android:id="@+android:id/progress"
    android:drawable="@drawable/starselected" />
</layer-list>

      

        
        
        
      

    

activity.xml

<RatingBar
style="@style/starRatingBar"
android:numStars="5"
android:layout_width="100dp"
android:layout_height="wrap_content"
android:id="@+id/ratingBar"
android:layout_marginLeft="130dp"
android:layout_marginTop="88dp"
android:stepSize="1"/>

      

        
        
        
      

    

Can anyone please help?