Retweet Icon on the Side of the Post

Login into Blogger.com

Click the Layout > Edit Html > Check In Expand Widget Templates

Find out the Line

<div class='post-header-line-1'/>

Copy and Paste these codes below the line which you found

<div style='float:right; margin-left:10px;'>
<script type='text/javascript'>
tweetmeme_url = '<data:post.url/>';
tweetmeme_source = 'dangerdiabolick';
</script>
<script src='http://tweetmeme.com/i/scripts/button.js' type='text/javascript'/>
</div>

Change the Name which is given in red to your Twitter user name ..

so that When you retweet it comes like this - RT@Your twitter name

You can see here in this blog - How the Icon Appears in the post - Check out the Top right of the post.