I bought a digital multimeter when I got my first RBA, an AGA T2. Turns out that I never had to take it out of the box. I could do everything I needed with just the Provari.
The Provari checks the coil resistance under load, meaning it fires current to the coil and then measures it. Be sure when first testing a new coil that you turn the voltage down to the Provari's
lowest setting.
Zen did an excellent tutor video on setting up a Genesis style RBA on a Provari. Study this well.
I've compiled a lot of important information for a new RBA user in this guide:
Advice and Tips for a New RBA User