Scott has seen an earlier version of this, but I've put up on line a revised edition of an armorial of all the MacMillan arms I've been able to find from all sources. It can be visited at
http://mysite.verizon.net/vzeohzt4/M...Armorial5.html

You'll see Rathdown's arms about halfway down the page. The empty images are for the arms of the chief's younger brothers; I don't have the colors of the assigned bordures for them just yet. My own arms are toward the bottom.