As of my last knowledge update in September 2021, the term "rectiformer" doesn't appear to be a widely recognized or established term in electrical engineering or power electronics. Therefore, I cannot provide specific information about how a rectiformer manages harmonics in DC applications because I lack information on its design or function.
However, if you can provide more context or details about what you mean by a "rectiformer," I would be happy to help you understand how harmonics are managed in power electronics systems, DC applications, or any other related topic. Please provide more information or clarify your query, and I'll do my best to assist you.