rdfEditor is currently tied to Windows because of its usage of WPF primarily because the text editor component from the SharpDevelop project is WPF only. Ideally at some point in the future a non-WPF build would be provided.
Some initial experimentation has been performed with the older SharpDevelop WinForms based editor but that has dependencies on GDI+ which mean it doesn't run under Mono. The alternative is perhaps to use the MonoDevelop text editor which is developed by the author of the old SharpDevelop WinForms editor but this would require a pure GTK# UI AFAICT