We've debated this topic quite a bit over the recent years. The tax regulations dictate more and more what options are available based on the amount of hours that the individual is working for you. They may first of all have to set up as a limited company if you don't want to pay NI and Tax. So ask an accountants advice on that.

Second is the contract itself. That is more important to consider ahead of a pay rate or percentage.

Lastly I have always paid a base hourly rate that was enough to have someone take the job. I'd then pay a percentage bonus on top depending on how much they generate for the clinic each month. At some times I did this by simply upping the hourly rate if they hit more than a certain amount of treatment hours. This gave them an incentive to keep their patient list growing and coming back.

A simple percentage can make staff become a little lazy, especially if the clinic is busy and they are guaranteed it. I'd look at the locum rates for ideas on the hourly rate to consider, perhaps hitting that as a high if they are really pulling their weight. but begin at the new grad starting rate as an hourly comparison. You'll probably find that the amount as a percentage of what revenue an hourly treatment might generate could be about 30% as an idea. I would not go above 40% if you want to stay in business but as a guide maybe 30-35%.

Anyway that's some of my thoughts on options.