It's been awhile since I've rigged a character but usually I don't parent a locator to an Ik handle. Instead I create a point constraint. Select the Ik handle, then shift select the locator. Then constrain>point>options box. Reset the settings and then checkmark 'Maintain Offset'. Click add or apply and that should do it I think.

If you havn't done so already, make sure you freeze transformation on your locator. That way, you can return your character back to the same pose by changing the locators transform nodes back to zero.