This latest update has broken it. Here is how to fix.

Go to "Rust\RustServerFiles\RustDedicated_Data\Managed"
And put the old system.drawing.dll back into there.

Next open the signartist.cs.
find and replace

player.EnableServerFall

with

player.SetServerFall

Where does one find the "old system.drawing.dll"?

Please do not attach random DLLs to forum threads. Also, the System.Drawing.dll is included with Oxide, and hasn't changed in years since it was removed from Rust.

Also, there is nothing to change in this plugin, so it sounds like you are using something custom.