Hi Adrian,
That’s a question best left up to you and your installer to decide. A physical examination of your finger would be required, and a half-way decent determination could only be made after that.
Of course, the finger is not the required location for the flexNT… it was only a location I chose. As far as install sites go, the fingers are difficult and risky compared to somewhere like the back of the hand. Is there a reason you want to install in the finger exactly?