To clarify - FPM, FKM and Viton are all basically the same material. Just different designations and Viton is DuPont's trade name.
Also note about the sealing lips on the crankshaft seal: The outer lip you see is not the primary seal. That is in fact a wiper or excluder that excludes foreign debris. The primary lip is deeper inside. So even if the seal is out just a bit, it should seal. But the wiper would not be engaged and could let debris in that would eventually damage the primary seal. The primary seal also has tiny ridges at angles that in theory channel oil backwards to prevent weepage (a very small leak). That's why there is an arrow on the face of the seal.
Also, it looks like there maybe a RTV silicone used on the OD of the seal. I am not a big fan of that and better to use a gasket dressing like Permatex #2 or #3 or similar. Technically the seal is designed so that it does not require any sealant on the OD but something thin like what I mentioned won't hurt. In this application, RTV silicone will create small cured globs that can end up inside the engine during seal installation.
