Originally Posted by
gojko88
It's your point of departure that sets the rules for entry. In your example, the SFO staff would verify your compliance with Finnish entry rules before they let you board the flight from SFO. Where you transit afterwards is of no practical consequence.
That's not universally true. Some countries (Sweden for example, in my personal experience) only look at where you're directly entering their country from regardless of initial starting point. Others consider everywhere you've been, even in transit, along the way. And other methodologies. You really have to carefully look at the rules from beginning to end of journey including transit rules as the other post noted.
Not familiar with Finland so I can't comment on that specifically