I just installed 5th string spikes on my RK this last weekend. I have any old banjo I practiced on first. It was pretty easy if you are good with your hands. I followed Jake’s video and deering’s advice on location.
https://www.deeringbanjos.com/blogs/faqs/10318861-how-to-install-spikes
I found some micro sized drill bits at Harbor Freight and used a hobby knife holder to hold the bit. I put the hobby knife holder in my drill since my drill chuck does not hold bits that small. A friend of mine builds model railroad trains so he gave me the railroad spikes. I recommend using some blue tape on the fret board before you use a mechanical pencil to mark the location to install the spikes. OR, just pay a luthier to do it for you. LOL