Here is the rss feed:
I click on it.
I get subscribe to feed using with a drop down box.
I choose yahoo and click subscribe now.
I go to a page that says: Get http://markhillman.com/feed/ on My Yahoo! and see the list of recent articles.
Then I click Add to My Yahoo and get this:
We couldn't find the RSS file you asked for http://markhillman.com/feed/
* - If you got here by clicking on an "Add to My" button, please notify the referring site's webmaster.
* - If you entered the URL yourself, please check that the URL is correct and points to a valid RSS file.
I don't know what the problem is.