You could follow the instructions for using the .conf file from there...
With .conf file (Recommended)
1. Append the configuration line to the file /etc/modprobe.d/hid_apple.conf creating it if necessary:
$ echo options hid_apple fnmode=2 | sudo tee -a /etc/modprobe.d/hid_apple.conf
2. Notify the hid_apple module to reload its configuration
$ sudo update-initramfs -u
3. Reboot
$ sudo reboot
and instead of running update-initramfs, you run dracut -f to build the initramfs.
Code:
cp /boot/initramfs-$(uname -r).img initramfs-$(uname -r).bak
dracut -f /boot/initramfs-$(uname -r).img $(uname -r)
The rc.local file was used to start up things uning sysvinit/upstart, and Fedora now uses systemd. While systemd does still run the rc.local file, it may disappear in the future.