"We need to win six out of our last seven games to stand any chance of making the play-offs," said McFarland.
"Today we showed the right spirit when our backs were against the wall in the last five minutes.
"But for most of the second half they over-ran us. They were stronger in the tackle and they kept putting the ball into our 18-yard box and making us deal with it."
After a dour first half marred by needless tackles and bookings, defender Steve Blatherwick headed the home side ahead from a Jamie McMaster free-kick in injury-time.
Rovers boss Brian Little went 4-4-2 at the break bringing on Eugene Dadi and Paul Brown in place of Ian Goodison and Danny Harrison.
The move had Chesterfield on the back foot and although Derek Niven forced a finger-tip save from John Achterberg, Rovers were firmly in control. On 49 minutes Paul Linwood was booked for an ugly lunge on Chesterfield full-back Alex Bailey.
Bailey limped from the pitch and although he resumed after treatment seven minutes later, he was withdrawn to be replaced by Alan O'Hare forcing a defensive reshuffle.
Dadi was proving a handful for the Chesterfield backline and McMaster found himself in the book for pulling down the Rovers substitute.
Rovers seemed certain to score on 66 minutes when Ryan Taylor's powerful shot from the right of the box was only parried by Carl Muggleton.
The ball fell sweetly for Rovers man of the match Paul Hall, but a last-ditch lunge by Niven saw his goalbound effort deflected for a corner.
McAteer won a disputed free-kick on 71 minutes which led to Rovers' equaliser.
As the Chesterfield fans accused the former Liverpool star of cheating, Taylor opted for a floated free-kick instead of a shot to allow Michael Jackson to head home at the far post.
With five minutes to go Dadi seemed to have wrapped it up for Rovers with a curling shot into the far corner from the edge of the box.
With one last effort Chesterfield won a point thanks to substitute Carlos Logan, who is on loan from Man City. His effort was covered by the Rovers keeper only to deflect into the bottom corner off the hapless Taylor.
Afterwards Little admitted: "I was disappointed not to have won. In the first half we had a good look at them, but in the second we had a go and I thought we had done enough to win.
"Once they had got the goal it was a case of showing what we could do.
"I was disappointed with both goals we conceded because we were not as solid as we should have been.
"But I was pleased by the way we stepped it up in the second half. We need to win games, although it looks as though automatic promotion is probably going to be beyond us."