How is the rating calculated?
I rate all players with a starting rate which is around 1000 points .
I then use a rating system which is very similar to the US rating.
If player A has a higher rating than player B and player A looses then he will be penalized by loosing points and if the difference in rating is very high then the more points will be lost. If the difference in rating is not meaningfull then the point lost will be minimal.