Our next drop of CM should include a modification to this sample where the submit button will be configured to submit as XDP. The process will be tweaked as well to deal with that change since it currently expects PDF, perhaps by re-merging this into a new PDF rendering.
If the process must be submitting PDF, this is more difficult to solve. The XDP would have to be modified to include the FormBridge XFO, and then saved as a PDF. This PDF would then require extending to permit the PDF submit operation. The PDF would then replace the XDP as the source template within the Lc repository, and the renderFormGuide part of the sample process would use it instead of the xdp when serving the client.