Summoning circles - how to use?

[Archonus1]

My GM has been periodically dropping summoning circles into buildings / ruins in our campaign. None of our casters besides me have really expressed an interest in using them. I'm thinking that I'd like to figure out how to do so effectively.

However, the literature is very unclear on this (obviously summoners can, but other than that) . If I want to do this, where should I put my points? Spellcraft? Knowledge (arcana)? ... what determines how much you know about them, and if / how well you know how to use one? I'm playing a wizard. As noted, the GM was actually surprised tonight when I used one (it had been used, innocuously, to bind a celestial plane tree to the floor of an elven temple) to first return the tree to its plane and then decided to use the circle to summon some creatures from the positive energy plane (which had been helping in one arc of the story). I just guessed how to do it (Elven caster, spellcraft (with bonuses) & knowledge (arcane) (with bonuses) both +15.)

Any advice on how to get some more skill here without taking a summoner level?

[HaraldKlak]

Firstly, there is definately no reason to take any levels of summoner for your wizard.

That said, summoning circles, following the rules, are relevant to the Planar Binding line of spells.
These calling spells, are basically the only option to "summon" are creature into our realm for a longer duration.

That said, your GM might have an idea with the summoning circles, and some other uses for them. You should probably work with him towards it.

For your character, you might visit whatever library or wizard college, you are close to, to study the workings of the summoning circles.