It is unsupported. Usually exporters only handles certain materials during export (typically "standard" materials with bitmap textures). Also raytrace material is not a material usually used in realtime applications, so there is no reason for them to support it.
Also rendering output and export output is two totally different things, so you cannot compare them, since the render output is made by the render engine you use, and the export output is dependent on both the format and the software used to display the output geometry.