CustomFit doesn't make patterns by other designers automatically. However, it can be used to create a custom version of another design, with a little bit of work up front on the knitter's part.
Here's a link to an article about how to "mash up" a traditional pattern with CustomFit. There are four simple steps and a worksheet to help you keep track of them.
If you have never made a CustomFit sweater, we recommend starting with one of the Basics Collection sweaters or a built-in design first.