Change Replace keyboard shortcut in Gedit
Your syntax for Karabiner is off.

This will work. Note that, like @klanomath, I have no idea if you're actually trying to use Command-H or Control-H, so you may need to change COMMAND_L to CONTROL_L on the third line.

        &lt;autogen&gt;
            __KeyToKey__
            KeyCode::H, ModifierFlag::COMMAND_L,
            KeyCode::F, ModifierFlag::CONTROL_L, ModifierFlag::OPTION_L
        &lt;/autogen&gt;


It also now occurs to me that in your version, within the code, your replacement command is Command-Option-F as opposed to Control-Option-F as specified in the name. So you might need to adjust CONTROL_L to COMMAND_L on the fourth line.