simple rating function

I am thinking of posting a simple rating for a product in a specific post.
to make it clear I make reviews for stuff and I would like to add a rating (lets say 7.5) and I want to be placed in the widget location where it will only show on the specific post. is that possible?
I took a look at widget logic abut couldn’t figure it out.
I thought of making a pic that has the rating but didn’t look good.
any ideas?
here is an example of what i mean:

the number can be highlighted so its not an image and it is located in the widget section.