How to create a rule to compare an order total with a custom field in a content type?
I'm assuming that your field_leveringsprijs (with "levering" = delivery, and "prijs" = price) corresponds to your minimum order price of your Restaurants content type.

If such field is not available as a token to use it in a Rules Condition, then the typical approach/solution is to use the Rules Action (not Rules Condition ...) "Fetch entity by id". So if you do have the id of the Retaurant available, just fetch the Restaurant (=some node of content type Restaurants). That will make all its fields, such as your field_leveringsprijs field, available for subsequent processing.

But, such Fetch entity by id is a Rules Action, so that's like you're too late to use the result of that Rules Action within the typical Rules Conditions (as you are trying to do in the data comparison shown in your question). The way to get around that, is to use either of following approaches:


Use the Conditional Rules module, which basically allows you to add a Rules Condition as part of the Rules Actions you want to perform. So using this module/technique, you'd specify something equivalent to "if order total is below field_leveringsprijs". And then add the actual Rules Actions you want to perform in that case (= perform a redirect, and show some message).
Create a Rules Component in which you execute (as Rules Actions) those actions such as that redirect and display a message). But which also includes a Rules Condition equivalent to "if order total is below field_leveringsprijs". And (this is crucial!) make sure to pass a "parameter" to this Rules Component, which will reprezent your field_leveringsprijs (with same data type). After you QA-tested your Rules Component, go back to your original Rule, and simply execute that Rules Component, by passing the appropriate value of the Rules Component parameter, using ... indeed ... your field_leveringsprijs (which you got via that "Fetch entity by id", remember?).