Looks more like some random teacher to me than Rider.

She's labeled as ライダーさん on the website.

She's doing a doctor cosplay.

Now with a translation for added funnies.

HAY GUYZ.

There's this game, it's called Rival Schools. It has this character, she's called Kyoko Minazuki. Play it sometime!

Then it's Rider cosplaying as Kyoko Minazuki. Note the eyes.