I don't think there is a blog feed FAQ. What exactly seems to be the problem? Your feed was working, but now it isn't?
It appears you have not entered a link to your feed but a static link to your URL. I believe, the latest version of Blogger is not supported at this time.
If you have the new version of Blogger a good (simple) workaround is to burn your feed in Feedburner and use that URL instead.
I'm using the same format and you can see it doesn't work properly - points to domain.com/atom.xml I have no idea why but that's how it's been ever since I updated to the newest version of Blogger.
What's being paid for? edit - nevermind, I get it. You can post the url and maybe someone can help. If it's the new blogger you're most likely sol.
Looking at the feed icon toward the top right of the homepage I can see that the RSS is delivered by: http://www.mortgagecalculators.org/feed/ Just like Shannon suggested. Try that exact link.