Scarifying seeds, is nothing to do with smoke/heat treatment. It means to abrade a hard seed coat (the exoderm), to make it thinner or to expose the inner softer bit of the seed (the endoderm). Hard coated seed are usually gently sand-papered, or the seed coat carefully sliced.
Smoke/heat treatment is different, sometimes called heat-stratification. I've heard that kettle-type BBQs (eg Webers)can be used quite effectively for this. Put a small amount of peat in the bottom, set it alight, and blow out the flames so it just smoulders. Put your plant pot where the burgers usually go (clay pots might be best), put on the lid and smoke your seeds. I've never tried this method, it was described in the UK CPS Journal a few years back, by A. Lowrie as a method of smoke treating difficult Australian Drosera and Byblis. Most growers use gibberelic acid (a plant hormone) to help germinate seeds which require heat-stratifcation, its much easier, don't know if it works with Roridula though.
Vic