I've been traveling in Europe for the past few months and I'm still confused about this! In most countries, it seems the common courtesy (according to tipping websites and the locals that I've talked to) is to leave a 5%-10% tip in restaurants, although it's not as "required" as it is in the US. Usually this is done by paying in cash and telling them to keep the change. However, what do you do when you pay by credit card? There's no tip line like there is in the US! What do the locals usually do? Do they leave a cash tip? Write it on the receipt? Don't leave a tip at all? I've tried giving a cash tip after paying by card in the past, but it's usually awkward and the waiters don't always understand what I'm trying to do. (And what if I don't happen to have any change on me?)
On rare occasion I've had the opportunity to add a % tip on the wireless card reader that waiters use, but that was mostly in Spain. I've only seen it once or twice everywhere else, possibly because my card is Chip-and-Signature, not Chip-and-Pin.
I'm sure there's variation from country to country, but it seems pretty much universally true that the recommendation will be 5%-10% in restaurants, and that there will be nowhere to add a tip on the credit card slip. What do I do to avoid coming off as stingy?