Rim tape must be wide enough to completely cover the spoke nipple holes. But, it must not be so wide that it interferes with the tire beads seating on the rim.

It must also be strong and stiff enough to resist being forced into the spoke nipple holes. Use a genuine rim tape (such as Velox) that has been developed for the task.

However, one of my local bike shops use two layers of Gorilla Tape (a brand name) which resembles duct or gaffer's tape which seems to work quite well. The Gorilla tape has the advantage that it can be torn into a strip that is the correct width for any particular rim.

I use Velox and have done so for more than fifty years.

Joe