If the system is set to use Networkmanager, wicked shouldn’t do anything. But …
Go YaST - System - Networksettings.
Set ( General tab) the networking to wicked.
Overview tab: tick the wifi card, click Edit
Set it to Dynamic IP address, Next
Leave the networking to Managed
Click Scan, select your ESSID
Select the Verification method ( most likely WPA-PSK )
Enter the passphrase ( key ) for your network
Click OK, OK and wait until done.
Reboot and you should be fine.
Mind, this means you will not see the Networkmanager in GNOME.
EDIT: I noticed it’s your first post here, so WELCOME !!
Like others have mentioned NM offers the obvious “turn-key” approach. Having said that wicked is very configurable (essentially an improvement of the traditional ifup framework), and so you could use a custom script in /etc/sysconfig/network/if-up.d/ to call wpa_supplicant as per this historic thread that may be of interest to you… https://forums.opensuse.org/showthread.php/402625-802-1X-wired-network-security