Centre Maddy Gordon played the full 60 minutes, shifting to wing attack in the final quarter with Whitney Souness precautionarily rested with a sore calf.
The Central Pulse midcourter backed up her strong defensive showing against Uganda and was energetic off the ball.
The Silver Ferns are the tallest side in the World Cup, over 12 centimetres taller than Singapore on average.
Kelly Jury - who spent the first and fourth quarters at wing attack - had a 28 centimetre advantage over her opposite.
It meant the minnows were forced to shoot from distance, with goal attack Kai Wei Toh proving particularly lethal early on.
Selby-Rickit and Ameliaranne Ekenasio had little trouble finiding space and dominated the aerial battle in the circle, leading the Ferns to a 17-7 lead in the first quarter.
Gina Crampton and Gordon made for a fast-flowing attacking midcourt, finding Selby-Rickit and Maia Wilson with ease through the second quarter.
Goal keep Jane Watson and Phoenix Karaka were at their best at the defensive end, strangling their opponents and at times forcing them to shoot almost from the perimeter. Watson finished with three intercepts, Karaka four and Jury three.
New Zealand kept Singapore to just two goals in the second quarter, making for a 41-9 halftime lead. Selby-Rickit shifted to goal attack in the third quarter, allowing Nweke to move into goal shoot.
They started fluidly but struggled for rhythm on attack after Nweke - who had already posted 12 goals in seven minutes - left the court. Selby-Rickit moved back into goal shoot for the final quarter as New Zealand put that shaky patch behind them.
They took a 10-1 lead to start the final 15, eventually winning it 19-5.
The Silver Ferns will play Wales in their first Pool G match on Monday night.
