The reality star, who has her own jewellery line House of Harlow 1960 and clothing range Winter Kate, claimed that she would not be qualified to advise Madden on what to wear.
"Men's fashion is such a different world and something I know nothing about. If I said, 'Vans', he'd probably be like, 'No, no. It's Nike'. So, it's better not to even to go there," she told WWD.
Richie also claimed that she has now started to be taken seriously in the fashion industry.
"The Simple Life started when I was 19 and my self-image has changed so much since then. Building credibility in fashion has been pretty organic in the sense that I'm finding out who I am as a woman and what I like and don't like," she said.
"There wasn't a day when I just woke and said, 'I'm ready to do this'. I knew in the back of my mind that this was something I wanted to do when I grew up."
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