http://feeds.macrumors.com/MacRumors-All
The RSS feed for MacRumors is above. Just copy and add this URL as a feed in your RSS reader and you should be set.
Are you using
this app called Free RSS? If so it looks somewhat out of date and limited in features.
if you don't mind, I will make a suggestion.
Set yourself up a free
Google Reader account for RSS feed management. Once you have an account go to the settings area and under Goodies (see my screen shot) drag the subscribe bookmarklet into your Safari toolbar. Once you have done that and you are on a web page you want to monitor with RSS, just click the bookmarklet and Google Reader will automatically find the RSS feed and offer to add it to your RSS subscriptions.
If you already have GMail, just go to the Google Reader URL and you will already have an account under the same login.
Once you have that setup, get a iPhone RSS reader that supports Google Reader sync. The app
Reeder is very popular and is $1.99. When you install Reeder you will be asked for your Google Reader username and password. Once that is entered the RSS feeds in your Google Reader account will be synced to the Reeder iPhone app.
Or if you don't want to bother with an app you can just go to the Google Reader URL (
http://www.google.com/reader) in Safari on your iPhone and read RSS direct from the browser.
Post back if you have questions about all this.
