Apparently this has changed and the recovery partition is now recommended to be after not before the C drive. In any case it shouldn't matter where it is.
Originally Posted by topgundcp
OEM deployment of Windows 10 for desktop editions
In Windows 10 Version 1511, we are changing our recommendation to have the WinRE partition placed after the OS partition. This allows future growth of the WinRE partition during updates. Today with the WinRE partition at the front of the disk, the size of it can never be changed, making it difficult to update WinRE when needed. We will continue to support having the WinRE partition located in different parts of the disk, but we encourage you to follow the new recommendation.
From the latest picture it looks like you can delete F and extend C to use this space. You need to confirm that the WinRE partition that is being used is the last one. To do this please post the results of reagent /info and diskpart list partition command for that disk as described here. windows 10 Anniversary upgrade created a recovery partition - Windows 10 Forums
If you do delete F and reclaim your space you'll probably need to re-register the RE image as the partition number will have changed.
To do this you would mount the partition in diskpart
and then from elevated command prompt
select disk 0
select partition 4 (probably)
assign letter = t
Deploy Windows RE
C:\Windows\System32\Reagentc /setreimage /path T:\Recovery\WindowsRE /target C:\Windows