It's a pity about Podcast Maker: I used it a few years back when I was running my podcast and it did an excellent job. Evidently it hasn't been updated for ages, and I gather it doesn't work with Mountain Lion.
It's not easy to find a replacement. RapidWeaver can create a podcast, though it's not ideal. iWeb can, but that itself has been discontinued and though it works at the moment we don't know how long it will go on.
Many people use WordPress, and it can create perfectly good feeds; however it's apparently quite difficult to use, and certainly it causes more problems that get asked about here than any other single method: always down to people having difficulty using it.
Many people use online services, which can be easy and effective but also leave you with less control over the feed - sometimes none at all. Blogger can work reasonably well (though I hate its feeds because they are all on one line which makes reading them when there's a problem nearly impossible), Podbean seems to work reasonably well, and Libsyn is tightly geared to podcasting and produces relatively few problems reported here.
You can handwrite the feed, which gives you the ultimate level of control, but it's very unforgiving: one tiny mistake can render it unreadable so you have to be closely aware of what you are doing, and it's not something I would recommend for everyone. My 'get you started' page includes a sample basic feed you can use as a template if you want to try your hand:
http://rfwilmut.net/pc