Ashton is convinced the Dutchman can be a hit at Carrow Road.
"You only have to look at his pedigree. You are not involved in the Dutch squad if you are not a good player," he said. "I think it was huge for Norwich to stay in the Premier League and even on the final day with the win at Manchester City they probably earned themselves £3m or £4m extra. If Norwich is able to do that year on year they will be able to pay more for players. They have shown a lot of ambition to bring a player like Ricky to the club.
"I think the big difference with me when I signed is that it was in the middle of the season. I literally didn't have too much time to think about it. One week I was playing for Crewe and the next I was in the Premier League with Norwich. The difference with Ricky is that he has had all this time really since the deal was first announced to think about what he is coming into, but he has been scoring goals in Portugal so he will be confident."