Foal sexing?

Ok I looked and there has been nothing since 2009 on this. Has anyone done this? I have one past the 54-70 day window and other will be in it in next few days. I heard you can do by transdermal after 100 days.
Would love to hear if anyone has done this in last few years!

There is a lady who sells in-utero foals that are sexed, every year.