Honestly, I'd go by a whole picture rather than one feature. There is a subtlety to early detection and often, newbies are completely surprised by the first crow. For example, this is pullet pink:
And this is cockerel red:
Same age. The color difference isn't so obvious at 8 weeks, right...
BTW, you want to see some butch legs?! Check out this gal:
She's an easter egger with trunks. Only about 3 weeks in this photo and her legs were as thick as my thumbs. Lays lots of big eggs the same shade as a robin's so yes, I'm sure that's a female.
Or this one:
Spur buds on a pullet...
Yes, the production reds DO tend to have thick legs and big feet. They also tend to grow very fast and mature early. The big tell for a sexing mistake would be a comb already going red at this young an age. Females will get red combs too but shouldn't be darker than a pink shade at 7 weeks...