Since Sasuke PS4 4.50 OFW went live, we've seen How to Set Up a PS4 USB 3.0 HDD, PS4 External Hard Disk Drive Restrictions, PSN Account Factors, PS4 Apps / Games via External HDD and now thenextslash shared a guide on copying PS4 game saves to a USB 3.0 external PS4 hard disk drive. 
Check out the tutorial below, to quote: How to Copy a PS4 Game Save to an External Drive
You will need:
Step 2: Insert External Drive
There are 2 USB ports on the front of the PS4.
Step 3: In the Main Menu, Go to "Settings"
Step 4: Click on "Application Saved Data Management"
Step 5: Select "Saved Data in System Storage"
Step 6: Select "Copy to USB Storage Device"
Step 7: Select Game to Copy
Step 8: Wait Until Transfer Is Complete
Repeat steps 4-8 for multiple games.
Step 9: Remove External Drive
That's it! Cheers to windrider42 for the heads up on this guide!
Check out the tutorial below, to quote: How to Copy a PS4 Game Save to an External Drive
You will need:
- PS4
- External Drive
- TV
- Cords
Step 2: Insert External Drive
There are 2 USB ports on the front of the PS4.
Step 3: In the Main Menu, Go to "Settings"
Step 4: Click on "Application Saved Data Management"
Step 5: Select "Saved Data in System Storage"
Step 6: Select "Copy to USB Storage Device"
Step 7: Select Game to Copy
Step 8: Wait Until Transfer Is Complete
Repeat steps 4-8 for multiple games.
Step 9: Remove External Drive
That's it! Cheers to windrider42 for the heads up on this guide!