user: Question: What's the Lowest Attendance with a Game site of Riverfront Stadium?
Columns: ['Week', 'Date', 'Opponent', 'Result', 'Game site', 'Attendance']
Types: ['real', 'text', 'text', 'text', 'text', 'real']
Sample row: [1.0, '1973-09-17', 'at Green Bay Packers', 'L 23–7', 'Milwaukee County Stadium', 47124.0]
SQL:

assistant: SELECT MIN("Attendance") FROM "Table" WHERE "Game site" = 'Riverfront Stadium';