As I found on the AF's website under "Gold benefits", I was thinking that NW offers 10kgs of free baggage allowance.
There is no extra baggage allowance benefit in SkyTeam.
From
http://www.AirFrance.co.uk/GB/en/loc...ite_gold.htm#7
Extra baggage allowance
* 10 kg extra baggage allowance on AIR FRANCE, KLM, Air Europa and Kenya Airways flights, in addition to your normal class of service baggage allowance*
* Baggage protection : your baggage is protected by a heavy-duty plastic film. This complimentary service is offered on long distance flights departing from Paris- Charles de Gaulle Airport.
* This extra baggage allowance is not available on flights where the baggage "piece concept" applies (baggage allowance determined by the number and dimension of baggage items).