Working With Postformats

I want to create a postformat for podcast type of posts, and I am 100% clear on how to do that in Montezuma. What I don't know is how to give a user the ability to mark his/her post as a podcast postformat in the WYSIWYG interface when creating a post.

Custom postformats I created simply do not get listed anywhere in the interface, so how is Montezuma to know that a given post is of a custom postformat? (the reason this is needed is because the homepage was designed to display a single post of each custom postformat I created)