How to add a custom NPC?

Hello, 

I'm trying to add CustomScientistNPC from chaoscode.io's Plane Crash event but for the life of me I can't get Skill Tree to award xp for it. I added it in like this to the config

"ScientistHeavy": 300.0,
 "CustomScientistNPC": 300.0,

and I tried to add it to the .cs like this 
AwardXP(attacker, config.xp_settings.xp_sources.CustomScientistNPC, npc, false, false, npc.name ?? npc.ShortPrefabName);

But no luck. Would you be able to tell me how to add a custom NPC in?

Side note. When the scientist is killed, in the console it is called HeavyScientist. I did try to add that in just the same way and that also did not work.

Ah ok.