Joining Van Praag in South America were fellow candidates Luis Figo and Prince Ali bin Al-Hussein, as well as current FIFA president Sepp Blatter.
Van Praag said he had received plenty of support, with the majority wanting change at FIFA.
"Well, the general feeling of my trip to South America was very good, it was very worthwhile," the Dutch Football Federation chairman said.
"I've been able to meet and to talk to everyone that I wanted to talk to.
"The reception I got was very welcoming and I'm glad to notice that everybody, without any exception, is in favour of change in FIFA.
"Nine out of 10 times they started saying that by themselves."
Van Praag said he would only stay in charge of FIFA for four years if elected.
While Figo has said he intends to have a 48-team World Cup, Van Praag said he was in favour of a 40-nation tournament.
"I think we should have a World Cup of 40 countries," he said.
"That is only 20 per cent of the participating countries in the world so that is not too much, that is a reasonable figure.
"I want that every confederation will get an extra seat, a guaranteed extra seat in the World Cup.
"I believe, and I will make sure, that the winner of the World Cup can defend its title again four years later, so they automatically have a place there.
"I believe we can raise the prize money, we can lower down the costs for the World Cup organisation - that is one part of it."
