
thewastedwalrus |

A character can have a whole load of rings, but they can only wear two magic rings for their effects.
A character can only effectively wear two magic rings. A third magic ring doesn't work if the wearer is already wearing two magic rings.
Changing the number of arms doesn't change this fact unless specifically mentioned otherwise.

Dasrak |

The matter is never explicitly addressed in the rules, which cover only typical humanoid PC's and animal companions, none of which have more than 2 hands with which to equip rings anyways. The vestigial arm alchemist discovery explicitly addresses the issue, but it's unclear as to whether it's conveying a general rule or something specific to vestigial arms. So this will definitely come down to a GM ruling.

Jeraa |

The number of arms/hands/fingers has nothing to do with the number of rings you can wear. There is nothing stopping you from wearing both rings on the same finger, for example. Having additional places to put a ring wouldn't change anything.
Also, nothing says rings must be worn on fingers. Fingers and hands are not mentioned. Toe rings would be acceptable. Put one through your nose. An earring could possible count as a standard ring. People assume it must go on a finger, but as far as I can see there is no limitation on where it can be worn. (3.5 D&D specifically said rings were worn on the hand, but Pathfinder changed that section of the rules.)
For that matter, you can wear any number of rings. Only the first 2 would function, however.

Jeraa |

Jeraa wrote:Belt of the Meridian.
Also, nothing says rings must be worn on fingers.
Which just means it is a poorly designed item. There already is no limitation how many rings can be worn. Nothing limits where those rings can be worn. That part of the belt is as bad as the original Prone Shooter feat, which removed a penalty that never existed in the first place. The belt is removing limitations that never existed in the first place (both the number and locations of rings).
The ability to switch between the rings, however, still keeps the belt useful. As well as the ability to keep a ring attuned, even when not currently functioning.