I'm looking for overhead pictures of the magic circles and runes used in the game, specifically the one used in summoning Aht. And assistance in this would be greatly appreciated.

You could just unpack the game files, you know?

And how do I do that?

I don't know that there are overhead pictures.
Here's the clearest picture I could get but I don't think it will be of much help if you're trying to decode the runes.

I'm not trying to decode the ruins. Rather I'd like to draw the circles but to make them accurate and precise I'd need an overhead view.