Before rooting your Oppo F3 Plus makes sure that your phone battery is 100%.
Before starting the rooting process create a backup of your phone, you will not lose any data from your phone by rooting, but it is better to create a backup for safety.
Installation via Unknown sources should be enabled on your device. To enable it to go to Settings > Security > Mark Unknown Sources.
Now Download Kingo root.apk for your Oppo F3 Plus fro