-Instructions from the original creators all credits to them: 

From: https://apple.stackexchange.com/questions/214995/how-to-use-3rd-party-usb-ethernet-adapter-with-el-capitan
(Also check the ASIX Kexts if you have compatible chip from the stackoverflow link)
As far as I understand, you can run a lot of generic ones that don't have Apple-signed drivers by disabling "System Integrity Protection" (SIP)

From: http://inkandfeet.com/how-to-use-a-generic-usb-20-10100m-ethernet-adaptor-rd9700-on-mac-os-1011-el-capitan

    Steps to get your adapter working if you've never used the adapter before in Mac OS 10.11 El Capitan.

        Uninstall the dozens of other drivers you may have installed in the process of trying to get this working.
        Unplug your USB adapter, and reboot and give yourself a clean slate.
        Reboot. As soon as the screen goes black, hold down "Command" and "R" until you see a black screen with an Apple logo and a white progress bar. Let go, and wait for your computer to boot into recovery mode.
        From the top bar, select "Utilities" and then "Terminal"
        In the terminal, run csrutil disable.
        From the top bar, select "", then "Restart"
        Once you're booted back up, download and install the drivers from the CD, kindly uploaded by this fine human being.
        Install from the x86_64 first.
        Install from rd9700-mac-driver.
        Reboot.
        Open your terminal, and run sudo kextload /System/Library/Extensions/USBCDCEthernet.kext
        make executable the permission.sh & run the permission.sh as sudo su.
        Reboot.
        Plug in your USB Adapter, with a live ethernet cable.
        Open System Preferences, and go to the Network Pane.
        Hit the + button in the bottom right, select the "USB 2.0 10/100M Ethernet Adapter", and hit add.
        You're all set! Your adapter works!
        Apologize to the people you care about for the things you've said over the past few hours. They won't understand, but they will forgive you.

I presume that any driver that worked for these types of things pre-Yosemite (10.10) would work for the ones in step 7.

See original page for a discussion on the security risks of using this method. But, if you need it to, and are aware of and OK with the risks, it works.

This worked for me on El Capitan (10.11) with a random off-brand adapter (can't remember the brand or if it even had one).

-This Seems that work with mac OS Sierra as well and need to run the ./permission.sh as sudo su, the driver is loaded properly. 