When you said 1/8" I assumed blade as the push beader comes in sizes 0,1,2,3 and 4. I just picked up a #3 push beader and the 1/8" beader blade. been playing with it and so far this is what I got. I use the blade to cut two, deep lines. I then bevel both sides and then use the push beader to crown the bead. I talked with Barry and he said most folks cut one line with a swivel blade and then follow that cut with one leg of the beader and let the other leg cut the second line or groove. From what I gather, the #3 is more difficult to use because of the size. He said the 0,1, and 2 are much easier to use. So, I'm going to keep on experimenting until I get an effect that I like. Hope this helps. Also check here to make sure you aren't confusing the push beader with edge beader. As in the knife both legs are the same on the push beader and one is shorter on the edge beader. Either way you need at least one swivel knife cut to follow.
http://barrykingtools.com/handtools.htm
Thanks,
Jon