The latest version of Apple's OS X, 10.9 aka Mavericks, has removed the RSS feed options from Mail and Safari.
They haven't announced a fix to this 'feature', but for those of you who have this technology please go to the App Store and search for RSS. At least one person is using RSS notifier successfully.
Of course, if you haven't noticed that the RSS feed is missing then you won't see this message either...
Mac RSS
Regarding reading RSS feeds on Macintosh computers, this issue is not new to the latest Mavericks. It changed a long time ago in a much earlier Safari upgrade. I switched to using the RSS reader Vienna, which I can recommend.
Richard Hunter