Clientside CSharp FAQ
Can I reference DLLs
No you cannot. The cs_packages folder will only compile .cs files
However, you may reference client rage-sharp.dll (in dotnet folder) to get auto completion and error-checking in Visual Studio/Code. Even if you get warnings, you will not compile the C# project anyway, you can still just save the .cs files.
Is it possible to use RAGE serverside JS with clientside C#
Yes