There are a number of ways to track an RSS feeds popularity. Unfortunately because of the nature of syndication the tracking is not always reliable or accurate. Use the followng to track the consumption of RSS feeds.
While it might be difficult to locate rss software free of charge, you can always hand create an RSS feed. There is a step by step tutorial at Make RSS Feeds that will walk you through the process of hand creating RSS feeds.
If you find the process cumbersome you may need to buy software that will handle all the encoding for you. Often the time saved by using the software, the software will quickly pay for itself.
A feedmix is simply a fancy way of saying that multiple feeds are merged into one feed. Often similar feeds will contain duplicate feed items, so its helpful that inconjunction with merging the RSS feeds you also filter the feeds to avoid duplicate content. There are a number of scripts in the RSS Scripts Directory that will make the process easier. Take a look at RSSmesh and RSSfilter.
