In that case you're sitting pretty, IMDO, because you can open an IRA directly with Rydex or Profunds. (I'm not sure about Potomac.)
By doing this you limit yourself to trading only that company's funds in that account, but there are benefits as well. For example, with either company you can trade every single day with absolutely no fees at all. Plus you get the latest cutoff times. Also, with Rydex, you can trade twice per day.