fixing toilet to floor

What screws should I use to fix my new toilet to my floorboards? The pan has two holes about 9mm across. I cannot find any screws with heads big enough not to go straight though.

Whats the trick?

Try to find some plastic screw caps (larger than the pan holes) and a couple of metal and rubber washers.

put the screw through the cap then the metal washer then the rubber washer. The rubber washer protects the pan, the metal washer stops the screw going through the rubber washer and the cap makes it look nice

pts sell brass countersunk screws with machined female thread in centre of head to take screw in cap. They also sell a kit of white plastic cone shaped liners which fit the shape of the countersing to protect your ceramic. A good wide flathead screwdriver is required to bridge the machined out part of the head. Predrill with a pilot for brass screws or you won't get them all the way in.

City plumbing sell plain flat head brass screws in various lenghts and diameters.

Many wc's come with a double ended stud, machine thread one end wood screw thread other, nylon washer and chrome dome nut. These are tightened down with a spanner. The drawback of this type is the stud remains in so to remove the toilet you have to lift it over both studs, not always possible or easy. If you can get it lifted slightly you can using a hacksaw blade cut the stud underneath, if you can't get toilet out any other way.

Make sure floorboards underneath are perfect and there are no pipes.