Is there a specific etiquette regarding who has to sign the "best wishes" card?
In France, AFAIK, no. But there are also "untold rules" one should follow, as it may backfire, anytime, in any possible way. Within a company, you shouldn't be rude, just be professional.
What does that mean? Well, 3 options:
- you know the person, and like her.
- you know the person, and don't like her.
- you don't (really) know the person (just "hi" sometimes, never work with them, or newcomer).
#1: any nice thing you wish to express to her.
#2: any casual/standard thing (or) / you don't sign. This is the tricky part. Better swallow the bitter pill and be nice, even if you don't feel like it, because others will know, and it may backfire. Don't put fuel on the fire. Any pleasantry will do the trick.
#3: any nice thing along the lines of: "we never had a chance to know each other, but still, all the best for your future" (something like that, with your own words), or just your name/ signature. Like point 2, any pleasantry will do the trick.
I have once not signed the card, but we had a loooong (bad) history of arguing, and "hated" each other (we never even talked professionally), so no one was really suprised. All of the other times it happened (5 or 6), I just did that (point 1/3), and never heard anything bad in return.
If I had to say which IPSkill it relies on, I'd say: nice and discreet, no waves. You interact with just what is professionally needed. Nothing personal. And remember that not telling the truth isn't lying, and not being nice isn't being rude.