A first for me with the C15 locomotive kit is a section in the instructions titled "About this kit - the confessional" where the manufacturer points out all the minor cock-ups in the model that might trip up builders.
Mostly these are things to watch out for to make the build easier but at the back of the model there is a mention of the rear handrail. There aren't any holes, you have to drill them yourself. It seems that there is a discrepancy between the GA drawings and photos. According to the former, there is no handrail or step. The photos show a handrail but no step. Another drawing shows both.
Measurements are provided for the holes and since a rear handrail seems logical I've drilled them . Getting these in the right place requires careful work with the ruler and then a drill. Making holes in brass isn't that easy - the bit tends to skid on the surface before digging in. Engineers would use a centre pop to make a depressing to locate the drill in. Belting things with a hammer is a bit vicious on the thin brass but pushing a sharp scriber (a good nail would do) into the location of the hole gives enough location to do the job.
The handrail is brass with split pins acting as handrail knobs. Lots of flux and solder applied from the inside means these will look OK, although my preference if funds permit, is to use proper turned knobs. Mind you, once the thing is painted and on the layout, I doubt anyone will notice.