Correct a Rhodesian stick was four guys - stick leader, two riflemen, and a MAG gunner. Why - That's how many people fitted into an Alouette III G-Car. However, that stick would be at least one of three and or possibly four dumped onto the ground. Later in the conflict, para sticks were deployed from a Dakota adding another five or six sticks to the mix. The key factors were however:
An Alouette-III K-Car with a commander on board who could see the battlefield and a 20mm cannon. That would orbit the contact zone and target the enemy accordingly with the 20mm while the commander could see for himself where his own troops and the enemy troops were located and issue orders appropriately.
A Lynx light strike aircraft would also be orbiting the contact zone and would either initiate the contact or strike as directed by the commander in the K-Car.
Superior training.
High motivation.
Close cooperation generated by familiarity with working with each other.
Numbers are not the be-all and end-all by any stretch of the imagination - well-trained troops, used to working together, commanded by someone who knows what they're doing with good situational awareness having support assets on call will always deliver out of proportion to their physical numbers.