this is the way ive made them before

start by carving a groove around the end of the handle (maybe even 2) that will keep the head from sliding off after its wraped with rawhide.

i recomend carving  another groove in the stone head. you dont have to but it would help hold it to the handle.
then put one rawhide strip over the top of the stone and pull the ends down tight so the stone is pressed against the end of the handle. then take another strip and wrap it around the handle under the stone untill you get to the head.

it may take a day or 2 to fully dry but if the heads still loose you can take thin raw hide strips under the stone and that should tighten it.

  I believe also what was done in that picture was the stone was pecked and perhaps ground as well to smoothe to make the groove down the middle of the stone around which you wrap the rawhide.  To peck it you need a rock harder than the one you are pecking and it needs to be kind of angular but round edges work too I find.  A piece of flint or chert that is kind of chunky and about the size of a lacrosse or tennis ball works best I find, but other materials like quartz or anything harder than the rock you are pecking will work, just hold it in your hand and wack the other rock with the pecking stone and you will find that small pieces are being pecked off the rock, over a good bit of time you can get a nice groove like that, makes your hands sore though, so wear a glove.  To grind and polish or sharpen a stone use a piece of wet sandstone.  Oh, and you should wet the stone for pecking too, keeps the dust down.