Can you do that? Yep. All you have to do to submit your posts automatically to Digg is to add the feed to your Digg account and verify it. You verify it by pasting some code into a new post that you make on your blog/page.
Like this:
actually the code is not visible because it is written as a HTML comment
Later of course you can delete the code or even delete the post not to confuse your readers. But I won't do it since my readership is so scarce and irregular and comes mostly from search engines. No regular readers here. Have I seen any new visitors from Digg since I added this blogs RSS feed to it?
Not really. Maybe it's still to early.