The deal is for $3 million but is worth up to $4 million including playoff bonuses, ESPN's Pierre LeBrun reports.
The Blackhawks did not contact Richards to pursue re-signing him, Chris Kuc of The Chicago Tribune reports.
Richards played 76 games for the Blackhawks and scored 37 points while averaging a career-low 14:53 of ice time per game. He added 14 points during Chicago's Stanley Cup run.
- Dan Gartland