On original Mauser CRF rifles they had to pick up the 1st round from the magazine and you could not just drop a round into the top of the mag and close the bolt. This made it impossible to load the magazine to capacity then get +1 in the chamber.
On Rugers, newer Winchesters, Kimbers and many others, they are CRF, but the extractors have been modified to allow them to snap over the rim. This allows you to top off your mag or load singly with out pressing the cartridge down into the magazine.
There are some people who will argue that this feature does not qualify it as true CRF. The bolt still picks up the round from the magazine, holds it all the way into the chamber and holds it securely until it is ejected with a blade ejector. I consider it true CRF.