As this has not been pointed out clearly enough yet:
Directories
Layout XML files for a custom module should be theme independent and thus placed into
app/design/frontend/base/default/layout
You can override any of these XML files in your custom theme, but in most cases, it is better to have an additional theme specific layout file that adds changes. More info: What is the correct way/approach to modify a Magento template? What is the correct way/approach to modify a Magento template?
File names
Note that those files are sometimes referred to as "layout.xml files", but layout.xml
is actually not a file name you would usually find in any Magento code. Your code works if you put your layout.xml
file in the right location (see above), but convention is to use the lower case module name:
rating.xml
or better
vendor_rating.xml
Remember that the layout XML files from all modules are in one single directory, so the name must be unique!