Yes, teams are always looking to add players.
You have several options.
1 - Check out the PLAY tab of the portal and click the fourth link down 'find a team'. There will be Upper House, and Recreational teams, that are looking for players.
2 - Check the season schedule on the COACH tab of the portal. Then find some games that close to you and go out and see the teams play - introduce yourself (SFYS can help with a connection too) and have a conversation about availability for the team.
3 - Reach out to the numerous San Francisco based clubs via a simple web search of 'SF Soccer Clubs'. Then ask around for references and check them out!
We hope this helps to get your player to right environment!