In case that you are not aware, you can actually show a series of “related” entries for your blog post based on keyword matching by using either the w-a-s-a-b-i or the Ultimate Tag Warrior (UTW) related post WordPress plugin. However, these related entries are not available for viewing in your RSS feed. In order to show them in your feed, you are required to modify your wp-rss2.php file, which is quite complicated.
With the WordPress plugin released by Solo technology, now you can add related posts to your feed easily. There are two version of the plugins. The first version is only can be used for the Ultimate Tag Warrior (UTW) related post WordPress plugin. While the second version is released with support for the w-a-s-a-b-i Related Posts plugin.
Installation
The installation is simple. Download the related plugin and upload it to your WordPress plugin directory. From the Administration Panels, click on the Plugin tab, activate the plugin from the Plugins Management page.
Download
- First version with support for Ultimate Tag Warrior (UTW) related post WordPress plugin
- Second version with support for w-a-s-a-b-i Related Posts plugin.
In order for your related posts to appear in your feed, make sure your blog is set to full feed and not summary feed. 
Tks for this tip. I love related posts cos I read them back myself. Hehehe, I got 2.5K posts so I forgot what I wrote 3 years ago, you see.
Hi Lilian,
Thanks for your comment in my blog
This is one thing which i should do right now .
i will be adding it soon…i am waiting to have sufficient related posts in my blog…
Unfortunately, I can’t get the Add Related Posts to Feed to download.
Will the second version work with WP2.3 and greater versions.
Hi,
Yes. I am currently using it now.
Will this work with new posts only or even with older posts in the feed