Understanding Additives can be difficult, I'll breakdown the math involved and run you through creating one from scratch.
Video Playlist: https://www.youtube.com/watch?v=UV-JKy4coXY&list=PLCUIHqJfP6i5mHhglBo5a7CHOoNEKPEsB
Join our Discord: https://discord.gg/38ceaJ67Eu
Project Files: https://drive.google.com/file/d/1LowqqQORLqu3sI5Iq-XoYtWu4Q-Aswvt/view?usp=sharing
00:00 Intro
01:20 Technical Additive Breakdown
04:42 Creating A New Project
05:50 PitFall #1 Preview Mesh
07:29 Creating Animation Pose
07:55 Modifying The Control Rig
12:23 Creating The Additive Pose
15:20 Additive Setting Explanations
18:09 Setting up Our Additive
18:30 Applying our Additive
20:36 End Result