That includes outscoring Fremont 9-2 in overtime and forcing four turnovers in the extra period to reach Saturday's championship game against Layton.
Riverton guard Jamie Smith turned in a 24-carat effort that included a 35-foot 3-pointer that beat the third-quarter buzzer and grabbing a rebound among four Fremont players after her missed free throw with 34.6 seconds left in overtime.
"It's something you always dream about, right," Smith said about her long-distance basket. "I got lucky to get the ball and shot it up."
Smith's basket put Riverton (21-3) up nine points the largest lead by either team. But Fremont (13-11) stormed back and tied it on Shelbee Molen's fourth 3-pointer of the game with 51 seconds left in regulation.
Richards scored 10 points after halftime, including two free throws that broke a 47-47 tie and gave Riverton the lead for the final time.
Riverton employed a box-and-one defense against Molen, who scored 14 points. But Fremont was hurt by Amanda Wayment's foul trouble she went to the bench with two fouls less than two minutes into the game.
"We just had to buckle down on defense," Smith said. "That's what we're known for, our defense. Offense comes from our defense, and we buckled down on their 3-point shooter and their posts."
Senior forward Whitney Saunders scored 14 points and grabbed seven rebounds for Riverton, which outrebounded Fremont 34-25.
And that means Richards and her teammates will break out the gold pens once more this season.
"I'm too excited," Richards said about reaching the final. "I can't even talk right now, I'm so excited. It means everything."