Kieran Agard netted the only goal of the game to move the Millers into the play-off positions and heap more misery on struggling County.
But after seeing Mark Bradley join a growing injury list with a groin strain, Evans admitted he may be forced to add to his squad before the transfer window closes.
"As a manager you always need two more players, but I think we maybe need about three now with the injuries we have had," Evans said.
"I'll speak to the chairman about getting players in and he's never said no yet.
"I think if we'd have come here and won five or six nil it would have been reflective of the performance.
"You have to give credit to the home goalkeeper, who stood up big and strong to make some wonderful saves, but our finishing should be a lot better.
"If we had been a bit more clinical, we would have sealed the points a lot earlier. Kieran should have had a hat-trick to be honest."
Midfielder David Bell had County's best chance of the match early on when he stung the palms of Scott Shearer, but that was as good as it got for the hosts.
Ben Pringle fired narrowly over the bar after 26 minutes before the Millers took a deserved lead when Michael O'Connor's free-kick fell kindly to the feet of Agard and he lashed home.
Agard should have doubled his tally soon after when the County defence left him unmarked in the area, but his header dropped into the hands of keeper Bartosz Bialkowski.
Evans's men should have been out of sight before the hour-mark.
A fine passing move involving Pringle and Alex Revell presented Agard again with the chance to put the game to bed, but Bialkowski's superb save denied the ex-Everton trainee.
- Sports & Recreation
- Kieran Agard