Uploading an vector image works the same as with a bitmap image: click Change Image (1), then choose Upload (2).
When uploading a vector image, you might see this message:
This means your file contains SVG features that Repper cannot turn into a pattern. For example, text is not supported, because we likely won't have access to the font file.
You have 3 options:
If you want to use a vector image you have uploaded before, go My Library (instructions) and look for images with a "V" indicator (for "vector").
In the Pattern panel, an indicator (1) above the current source image tells you whether your current image is a vector or bitmap image.
If it is a vector and it has unsupported features, it will show an exclamation mark (2). Hover over the indicator to see which features are not (or only partly) supported.