If u r using template provided with blogger , than doing this will work , but if u r using any custom or third party template than u need to add some code for this to work
Go to edit HTML and check the expend widget template
Search for this line of code:
<span class='star-ratings'
><b:if cond='data:top.showStars'><div
expr:g:background-color='data:backgroundColor'
expr:g:text-color='data:textColor'
expr:g:url='data:post.absoluteUrl'
g:height='42' g:type='RatingPanel'
g:width='180'/></b:if></span>
Now search for following code:
<b:include name='feedLinks'/>
Copy the following code and paste after the line mentioned above:
<b:if cond='data:top.showStars'>
<script src='http://www.google.com/jsapi'
type='text/javascript'/>
<script type='text/javascript'>
google.load("annotations",
"1");
function initialize()
{google.annotations.setApplicationId
(<data:top.blogspotReviews/>);
google.annotations.createAll();
google.annotations.fetch();
}
google.setOnLoadCallback(initialize);
</script> </b:if>
Now u'll be able to star ratings in ur posts Njoy
For more info read this blog