On MacOS with Tunnelblick.
brew install oath-toolkit
mkdir ~/Documents/my-vpn.tblk
cp ~/Downloads/profile.ovpn ~/Documents/my-vpn.tblk/
printf "#!/bin/bash\n/usr/local/bin/oathtool --totp -b -d 6 {OTP_KEY_HERE}" > ~/Documents/my-vpn.tblk/static-challenge-response.user.sh
chmod +x ~/Documents/my-vpn.tblk/static-challenge-response.user.sh