For this ritual you will need bones that are easily broken (chicken bones work great), something to smash them with, a bag, and the ability to visit the property of your victim.
Dry the bones in the sun (or bake them briefly in the oven) until they are dry.
Meditate upon your anger and hatred with the bones in your lap. Set them down and say,
"These bones of life I do now crush!"
Take a hammer or something similar and crush the bones, imagining that they are your enemy. When you're done sweep them into a bag.
Travel to your enemy's property and sprinkle the bone dust around his house. If you absolutely cannot even toss a handful onto his lawn you can sneak a tiny pinch into something he owns like a backpack or shoe. You could even drop a tiny amount into his hair. Once it's been deposited return to your temple and ring a bell 3 times (or beat a drum or clap your hands). Say,
"I call upon the Ancient Ones from the great Abyss to do my bidding!
I invoke Cuthalu, God of Anger; hear me now!
Bones of anger, bones to a furious dust,
These bones make rage of my enemy!
Bring him pain! Bind him! Crush him!
With these bones I do now crush his spirit!
Make mine enemy turn to dust, torment, fire!
With this hex I curse his soul!"