David Goodwillie struck an equaliser in the fifth of six minutes of injury-time to prevent former Scotland boss Craig Brown leading the Dons to three successive victories.
`Houston said: "I have to credit the players for their ability to keep going until the sixth minute of injury-time.
"I thought we were poor and we never played anywhere near the standards that we set ourselves.
"We were poor all over the pitch and defensively we never won enough headers and we allowed Aberdeen too much space to run at us.
"Aberdeen played better than us but I'm delighted with the resilience shown by the players to keep going and get an equaliser with a quality finish by Goodwillie."