Error while compiling: PlaceholderAPI.cs(1750,31): error CS0433: The imported type `Steamworks.SteamServer' is defined multiple times

any help appreicated. 

That error means that you have multiple Steamworks DLLs in your RustDedicated_Data/Managed; it isn't a plugin issue. If you are on Windows, delete the Facepunch.Steamworks.Posix.dll; if on Linux, delete the Facepunch.Steamworks.Win64.dll.

Thanks