Here's an example of the egg spot I'm talking about
Here's the same one to show the shape of a female. Note the small dorsal, and the anal fin that doesn't angle down. Normally females will have shorter ventral fins... but a few of mine are just weird.
Now, here's an example of a male PK betta. Not the clearest picture in the world... But notice his dorsal is much bigger, his ventral fins are much longer, and his anal fin angles down. Also a good indicator is to check for a "beard" when he/she flares. When the gill flaps fan out, it'll look like a totally seperate flap that folds out underneath his/her chin.
Example of a male's flare:
And yes, these guys/gals are all mine. ... Although the female up top passed away in February. :/