What are the legal requirements to be a Reiki Practitioner in the state of Oregon?

I don't believe you are required to do anything particularly special in order to practice as a Reiki Practitioner in Oregon as opposed to any other state. Obviously, you will need/want to master the art of Reiki healing beforehand. After that, there are a few options:

1. You will most likely want to be recognized by the American Board of Holistic Practitioners. This will require formal training and certification if you plan on working in a professional medicinal setting. There are Holistic Studies Institutes that will provide you with a certification as Reiki Practitioner and Reiki Master.

2. Another route is just to become a teacher of Reiki healing. You may still want to become certified for prestige reasons, but this should only require confidence that you've mastered the art and are willing to take on a class (and a business sense I suppose).