It also helps to corner him in the trees, rather than running up and "wuss-slapping" him with the potion, although I've done this before as well. He only walks a certain distance along the lakeshore, then turns around. It's also fun to ask him additional questions; you get some good responses from him.

-Sazerac

Hey , i have a side quest that tells me to deliver a potion to mekdawa, i found him no prob, but i cant figure out how to give potion to him, i try to give him but he always walk away saying ukabu need toad blah blah blah, anyways, anyone can help out there?

Try highlighting the character with the quest. Open your use/give window (left side of screeen). Click on 'give', then scroll through your inventory using the arrows on the little give window until the potion bottle shows in the window. Keeping this window open, approach Mekdawa and click on him. When you hear him say "Toads need this!" you know you've successfully given it to him. If you have more than one with the potion quest, repeat steps after highlighting the subsequent character.