Blogger World

Log in to Feedburner, using the Google account that owns the feed.

Click on the name of the feed you want to provide a subscription tool for.

Choose the Publicize tab.

Choose the Chicklet Chooser option, from the left navigation bar.

Choose one of the options shown:  the default one is the standard-size RSS-radar-button.

Scroll to the bottom of the screen and either Copy the HTML that is shown, and add it to your blog in the same way that you would add any other 3rd party HTML, 

OR

Choose Blogger from the drop down list beside "use as a widget in", and click Go.

This takes you to a Blogger screen where you can choose which blog you want to add the gadget to (if your current login has more than one), and what title to use for it.

When this is done, click Add Widget.  

This takes you to the Design > Page Elements tab, where you can drag-and-drop the widget to wherever you want it.
(When I tried it just now, instead of the layout screen I got a "bad request" message.  However pressing Save and then View Blog brought up the blog with the gadget showing, and I was able to go back and edit the layout later on).