How can I hide exposed countersunk screws in kitchen cabinets side panel?
You can use wood filler if you're painting the cabinets. Use a putty knife to apply, and then sand even after it dries.



Alternatively, if you're going to stain the cabinets, you can use a plug cutter that matches the countersink diameter. Using matching scrap wood, cut a plug that has a similar grain pattern, and lightly tap it in the hole after applying a thin layer of wood glue. When it dries, you can use a chisel to cut it flush or nearly flush, and then finish up with sandpaper. Then you're ready to stain!



If I remember correctly, this 5/16" diameter plug cutter works well with a #8 countersink hole. (You may want to check, it's been a while since I used that combination on a project.)