Don’t worry, it won’t be a little Frankenstein! It will probably be cute and wonderful, just not a high production egg layer when you actually make a sex linked chicken.
If you have a sexually mature rooster, chances aren’t your eggs are fertilized. You can tell when you crack them open and see a little white bullseye on the yoke. Obviously you can’t hatch ones that you crack, big I believe you should give the hen a few days and then candle the egg.
I do believe she is a sex linked hen. Rhode Island reds are typically not that big and they are much darker.