Follow these steps below to enable multiple SSH keys on your device with UNIX Based OS (MacOS/ Ubuntu/ Debian etc.). Suppose, you have two different users/ accounts, one is personalAccount and another is companyAccount. And you have already a default key configured with personalAccount. (If you haven't set up your default ssh-key yet, please follow this article before going ahead with these steps described below.)
Generate a new ssh-key for your companyAccount.
cd ~/.ssh
ssh-keygen -t rsa -C "your_email@youremail.com"