I get this really annoying.

PrintToChat is from our DLLs, you should be referencing them all. For any Rust-specific code, make sure you are referencing the game’s DLLs relevant to what you want, which in most cases is Assembly-CSharp.dll and many of the Facepunch.* ones.

I can't find Facepunch.UnityEngine.dll

Merged post

What do I need to reference?

Facepunch.UnityEngine.dll is included with the Rust Dedicated server, and is located under RustDedicated_Data/Managed.