How to properly calculate required specs for Induction Heating/Furnace unit

Need to investigate an Induction Furnace for Heat Treating some parts. I've used Induction Furnaces a fair amount and used to make custom coils for the parts I was Heat Treating fairly commonly, so it's not new to me. However, it has been a few years, and I've forgotten much of the technical stuff that I used to know or have access to, so I am having a hard time recalling just how a unit was sized properly based upon its dimensions and area to be affected.

I know I can make the inquiry with any one of a few places that make them, but I'm already dealing with a number of machine tool builders at the moment and don't relish the concept of yet even more email and phone calls resulting from the effort.

Anyone here deal with this and recall how to calculate the power and frequency range required?

Thanks.


EDIT - never mind. Google started cooperating. Feel free to delete. Seems we cannot do so.