Set gopath in oh-my-zsh

Since I am not using bash but oh my zsh, I was confused in the first place, what would be the right way to set an additional path.
The answer is the custom folder and a simple .zsh file.

cd $ZSH_CUSTOM  
vim additional_paths.zsh  

… and within that file it would be in my case:

cat ~/.oh-my-zsh/custom/additional_paths.zsh

# Add go to path
export PATH=$PATH:/usr/local/go/bin