This post shows you how to create PCB slots using KiCad. It's a follow-on from my general Slots article.
In the pad properties, set the "Pad type" to "NPTH, Mechanical", set the Pad shape to "Oval", and set the Drill shape to "Oval". Then edit the pad X and Y to be the dimensions of the slot, and set the drill X and Y to be the same size:
I think you don't need to set the layer.
Next we're going to trace around the outline of the slot with thinner lines, in the "Edge Cuts" layer. Select "Edge Cuts", then the line tool, and do the two parallel horizontal lines:
Now draw the ends of the slot using the arc tool:
Pro tip: Rather than using four 90° degree arcs, you can use 2 180° arcs by drawing one arc then setting the arc angle to 1800, which is 180°'s worth of 1/10° increments:
Now that we've traced all around the outline of the slot, erase the inner stroke from the Eco2.User layer:
And finally reduce the line width of the outline strokes in Edge Cuts:
Here's the finished outline done with 0.001mm lines:
This outline will then be present in your outline layer after gerber generation.
Thanks to Honeyclaw for the pictures. Used with permission.