A CBR is nothing but a RAR file renamed CBR (and you use pixel comic or cdisplay to read those comics). What you do is select the folder, make an archive - either zip or rar, and rename the extension to CBZ (if zip) and CBR (if rar). Thats it.
As for the PDF, there are many tools available - i.e foxit PDF editor or Abby Finereader (its OCR software, but its easy to make a pdf, don't do the OCR, just save PDF with background images), that can easily create such files.