More importantly, if she is unfamiliar with shooting rifles, teach her how to pull the rifle tight into her shoulder and lean forwards into it. Don't just hand her the rifle and stand back. If it's not pulled tight into the shoulder it will recoil backwards and painfully smack the shooter. If the shooter is not leaning into it they will be unbalanced and pushed backwards by the recoil. Make sure new shooters fire rifles standing up, first, as shooting sitting down requires an entirely different technique to properly handle and mitigate painful recoil.
An unstable platform compounded with the aforementioned smack will make the shooter unlikely to have a good time. Almost anyone, man or woman, can shoot a full power rifle or shotgun if they are taught proper technique.