All you have to do is enter your feed in the form and it will generate a button to put on your blog sidebar.
Or get it as a bookmarklet.
For more of these see an earlier post, RSS button clutter.
Besides being a multi choice button for feed readers, it also does the same for bookmark services…this time enter the page URL instead of the feed, into the form…I entered my blog homepage
…when users click on this button, they can bookmark the page in their favourite service.
It would be good to have it generated automatically for every blog post, see more for this type of thing.
Here is an example using Socializer: