Not sure about all the confusion here- LH sells F on FRA/YVR from March-October every year. On some dates, they use a 744 as they have loads sufficient (I don't know by class- however total number of pax) to justify it. It is not that common- however not that unusual.
YYC use to have F, however they dropped it for low demand.
YYZ has some kind of F, although I don't know when/how it works.
LX with YUL is introducing year round F service to ZRH.
In the spring/summer/autumn, the loads to YVR are very strong from Europe.
Around Christmas, there was a two week period last year where LH was flying a 3 class aircraft, however F was available to anyone with a paid C ticket who made the correct ASR- in this case, service was C, and throughout the flight the curtains were open etc.
LH seems to follow the Canadian market quite closely- so if there is enough demand for F, it will probably appear.