The Orlando Pirates attacker started the knockout tie, having appeared just once in the group stage as a substitute in the 1-0 defeat to Egypt.
He was close to finding the target early on against Cameroon, in a good spell of pressure for South Africa where they looked dangerous and created a number of goalscoring chances.
But goals from Junior Tchamadeu (34') and Christian Kofane ultimately sealed the result at the Agdal Medina Stadium, with only substitute Evidence Makgopa (88') on target for South Africa late on.
Reflecting on the game, Mofokeng told SABC: "I think that [missed] chance could have opened the game for us. I take responsibility that I should have scored."
The player added: "We created many chances and just needed to use them. I think it's not the first time we've chased the game, but we've kept believing we can go beyond the Last 16, but it was not to be."
"But our spirit remains high, we just need to continue playing the way that we are playing and use our opportunities [in future games].
Former Nigerian international midfielder Mutiu Adepoju says the Super Eagles have been improving with every game at the Africa Cup of Nations and expects the team to see off Algeria in the quarter-finals.
Benin coach Gernot Rohr said he was proud of his players despite their 3-1 defeat to Egypt in their Africa Cup of Nations last 16 clash on Monday.
Ivory Coast midfielder Amad Diallo says he was "humbled" to scoop a third Man of the Match award in the Africa Cup of Nations last 16 win over Burkina Faso on Tuesday.
Egypt coach Hossam Hassan knows his team will need to be at their best to make it to the semi-finals of the Africa Cup of Nations after being pushed all the way by Benin in their last 16 clash.
