The AG-Guys stuff is 50mg/ml. Use a syringe to measure it out rather than the dropper. I checked the dropper once and it's closer to 0.5ml. Just use a syringe.
I just looked at the AG-Guys site and I suspect that you get 50mg/ml of clomifene citrate rather than 50mg/ml of clomifene as citrate. That said, I (or my rats) have done several PCTs with their clomid at 1ml ED and it seems to do the job.
You'll also find with the liquid clomid that it often crystallizes out of solution. If you see this has happened, you should stand it in hot water until the liquid is clear again else you'll be under-dosing. During cold weather, you might need to do this twice a week; during summer not at all. You'll also find that it tastes absolutely foul.