Hadn't revisited the programming in some time (I got my original Raven several years back from PrimeKB), but I tried a few things and this is what worked for me. The instructions used to be on the PrimeKB webstie, but the page is gone now. (I didn't try the QMK configurator)
1. Download O2D (The one I found and worked for me is here:
https://duck0113.tistory.com/84)
2. Make your keymap and compile it (In the O2D menu, select File> New> O2D Viper/Eagle Custom v1.x) Create the layout you want, and then choose File> Save. Give it a unique name so that you can locate it easily. Mine saved into the Downloads folder.
3. Get the keyboard into flashing mode (The Duck site says CapsLock is the key to enter bootloader mode on these PCBs and it worked for me. Hold down Caps as you plug in the board. If you have QMK Toolbox open, you'll see the "Atmel DFU device connected" message)
4. Flash with QMK Toolbox (or Flip). PCB uses the standard atmeg32u4. Select your firmware created from step 2, and flash it.
Type away on your lovely keyboard