I’m fitting some flooring in the kitchen

Trying to work out how to get the round bottom stair marked out to cut

I used a length of wood with a pencil attached to it, but as you can see by the marks on the flooring, it looks like an earthquake reading

Any other ideas?

I want it spot on so I don’t have any gaps, I’ll leave an expansion gap at the opposite end

http://www.screwfix.com/p/forge-steel-profile-gauge-10/28558

a profile gauge and a jigsaw will make light work of that.

Trim a template out of cardboard. Keep offering it up until it fits perfectly and then tape the cardboard to your flooring and trace the curve.

Also clear silicone is your friend if you do end up with a tiny gap.

“trim a template out of cardboard.”
take your time and do this