When it comes to working as a football referee, she is fine with being "just one of the guys."

In her first year as a PIAA official on the gridiron, Chris Donnelly has blended seamlessly with her black-and-white-striped brethren.

"She's been in the big games, and she's delivered," said Tommy McClain, a legend in local refereeing circles and crew chief in District 12's top contests. "She was invisible. I didn't even know she was out there. And, as a referee, that's your goal."

With McClain serving as head referee, Donnelly, 43, was side judge and part of a "six-man" crew in a recent Friday night clash between Public League Class AAAA powers George Washington and Northeast at Charlie Martin Memorial Stadium.

Late in the fourth quarter, Donnelly, positioned on the Eagles' sideline, reached into her back pocket and tossed a flag for pass interference against the host Vikings. The call, which moved the ball 15 yards closer to a potentially tying Washington score, drew the ire of the black-and-red-wearing faithful.

But Donnelly (head linesman Keith Foster also threw his yellow hankie on the play) got it right, which Northeast coaches acknowledged when the dust had settled after their 13-6 division-clinching victory.

During the game, with the scoreboard clock sometimes malfunctioning, Donnelly calmly kept longtime Washington coach Ron Cohen and his assistants from blowing their tops.

"I told them, 'I'm watching it like a hawk. Don't worry, I've got it,' " said Donnelly, an Oxford Circle native. "They were calling me, 'Ms. Official.' People don't know what to call me. It's so funny."

Last month, Donnelly was the line judge for a Public League duel between Northeast and host Frankford. Except for McClain's reprimanding a few players for unsportsmanlike behavior and trash talk, things went smoothly for the gang of six.

Of Donnelly, a counselor and girls' basketball coach at the Academy at Palumbo in South Philadelphia, side judge Frank Powers said: "She knows the game. She does a really nice job."

Despite his team's 14-13 defeat, Frankford boss Mike Capriotti also gave her high marks.

"She was very good," he said. "She was on top of things, knew what she was doing. She's as good as anybody we ever had."

Two years ago, Donnelly began refereeing weight-class and CYO football as part of the Association of Registered Conference Officials (ARCO).

"I still remember attending my first meeting," she said. "I was definitely nervous. I was the only girl."

The Fox Chase resident, who passed the PIAA exam last year, is one of only three females among the 110 or so District 12 football refs. The others are Valerie King Smith and Ruthy Rotimi.

"One of the things I enjoy the most is the camaraderie between officials," Donnelly said. "We're a team out there. We're either going to sink or swim as a team. Collectively, we want to make it a good game for the players, coaches, and spectators. We work together to accomplish that."

The diminutive Donnelly - "I'm little but fast" - brings hands-on experience to each game. She played safety and cornerback for six years in the National Women's Football Association (NWFA), with the Philadelphia Liberty Belles, and, later, the Philadelphia Phoenix. A serious right knee injury ended her playing career in 2007.

Her mother, Madeleine, "hated that I played football." And her father, Jack, a man's man who owned a steel construction business? "I think he secretly liked that I played," she said, laughing.

Donnelly has officiated basketball games, including Catholic and Public League varsity contests, for 18 years. She played hoops at Little Flower and briefly at the University of Scranton while earning a degree in health and human services.

The former co-owner and general manager of the Phoenix (now the Firebirds in the Independent Women's Football League) said refereeing football "was a natural progression. I got into it because I love the sport, still miss playing it. This is a safer way to be on the field and be involved."

As for her quick rise up the officiating ladder, Donnelly thanked McClain and others, including ARCO assigner Rick Levans, recently diagnosed with throat cancer, and veteran District 12 refs Bill McKeever, Joe Kenney, and the Gallagher brothers, Tim and Ernie, for their support and encouragement.

In December, Sarah Thomas, positioned as a line judge, became the first female to officiate a Football Bowl Subdivision postseason game. At last count, the 36-year-old was one of five women in the top college tier. The hardworking Donnelly has similar aspirations.

"I want to ride this as far as I can," she said. "But I don't want to get pushed through just because I'm a female. I want to be there because I deserve to be there."

Contact staff writer Rick O'Brien at 610-313-8019 or robrien@phillynews.com.