See the link above:
Plain and simple just don't use dropbox for our podcast files or RSS feed hosting if you actually want your podcast to work well with iTunes and iOS devices.
Dropbox is not meant for podcasting.
Most of the solutions create a blog with a way of adding media files, and then generate the feed from that. You could handwrite the feed yourself - it's not horrendously difficult, but it is unforgiving - a simple error can wreck it. You may find it helpful to read this page:
I used Podcast Maker a few years back and it worked easily and very well, but it does seem that it hasn't been updated for ages and I'm not sure it's reliable with the latest OSXs. Some people user WordPress but though it can work it also causes a lot of problems - mostly probably misuse, but it does seem difficult to use. There are online solutions like Blogger but they give you very little control.
Feedburner usually works by your adding an existing feed to it, but your may be able to construct the podcast directly in it.
Libsyn is specifically designed for podcasts - Rob works for them and can advise specifically.
With libsyn we help you manage the RSS feed - you just upload the media file - add a title and description and hit publish - it is that simple.
While we provide you an optional blog page - there is no need to use that blog page - you can just use libsyn to upload the media files and update your RSS feed.