Runes and the Middle mouse button

[Tay]

I don't have a middle mouse button. So, I have collected many runes but i'm unable to equip them, Is there a way besides the middle mouse? I have changed the middle mouse in settings so I can use the lock on ability, but it doesn't work for runes. if it's not possible then runes are useless to me. And, the internet doesn't suggest anything either.,