Kinetic Form not a polymorph effect?

[HibikiSatsuo]

It doesn't say it is in the ability description anywhere that I can see. Any errata about this or can you stack Enlarge Person and Kinetic Form?

[Mark Seifter]

It's not a polymorph effect, but it's a "magical effect that increases size", which don't stack with each other anyway (weirdly this rule is really hard to find). (also it sets your size to a particular size, so even if magical effects did stack, you'd have an order of operations issue, and based on surrounding your altered body with elemental matter, I'd say there's a strong case that the order of operations would apply kinetic form last anyway).

[Torbyne]

That's it people, straight from marks mouth (keyboard) thunderbird is a go... Also thunderhorse.

[Gauss]

You cannot combine polymorph and size changing effects.

CRB p212 polymorph wrote:

You can only be affected by one polymorph spell at a time. If a new polymorph spell is cast on you (or you activate a polymorph effect, such as wild shape), you can decide whether or not to allow it to affect you, taking the place of the old spell. In addition, other spells that change your size have no effect on you while you are under the effects of a polymorph spell.

Additionally, enlarge person does not stack with size altering effects.

CRB p278 Enlarge Person wrote:

Multiple magical effects that increase size do not stack.

So, the following does not work:

Enlarge Person + Polymorph (violates both rules)
Enlarge Person + Kinetic Form (violates the enlarge person rule)
Polymorph + Kinetic Form (violates the polymorph rule)