There were also five invitation places available to the next highest placed swimmer of nations not already qualified from each of the five Continental Regions of Europe, Africa, North America, Asia and Oceania.
With Australia already qualified, New Zealand was offered a place as the next highest placed nation from Oceania - as Radford and Webby did not qualify directly as one of the top 10 finishers.
The selection policy of Swimming New Zealand and the New Zealand Olympic Committee criteria is that a swimmer needs to show evidence of an ability to finish in the top 16, with a potential for a top eight placing in Rio.
If Swimming New Zealand selectors determine Radford and Webby meet the over-riding criteria, they will then nominate with supporting evidence to the New Zealand Olympic Committee selectors by Friday.