Dot goes to the back. The R# in the chart shows which match each other in height. A keyboard has a natural curve to the profile of the keys, so what you need to do is identify the large keys (backspace, enter, shifts, tab, etc) and then use the chart and find enough of the small 1x1 keys to complete the row. The top two rows of the keyboard are the same profile, and the bottom two match each other, so it's easy to start from there and fill it in, as the keys go from taller (R4) to shorter (R1)
I had also not realized until just now that both of my IMSTO sets don't have identifiers on the underside, I'd never checked since mine are printed.