function checkSize(thisform){
	// place any other field validations that you require here
	// validate myradiobuttons
	myOption = -1;
	if (!thisform.size.checked){
	for (i=thisform.size.length-1; i > -1; i--) {
	if (thisform.size[i].checked) {
	myOption = i; i = -1;
	}
	}
	if (myOption == -1) {
	alert("Please select a size and colour to add to your basket");
	return false;
	}
	}
	// place any other field validations that you require here
	thisform.submit(); // this line submits the form after validation
}