I'm trying to render some SVG and it doesn't show up at all in the PDF. It's SVG that's been generated by a HighStock chart. I've successfully rendered other Highcharts output so I'm a bit mystified by this.
This appears to be a width/height/viewBox issue scaling the SVG too small, which we have corrected for the next release of Prince; see the attached PDF files below. A quick workaround is to add viewBox="0 0 600 400" to the root SVG element.
Pixels in SVG are generally 96dpi, the same as in CSS, but Prince has treated SVG pixels slightly inconsistently, so they might be 72dpi in the version you are using. The next release of Prince will treat SVG and CSS pixel units more consistently.