Adding Pages to a User's List
There are a few different ways to save a page to a user's list. The best one depends depends on your type of application.
API
If you are building your own application and would like to provide a native saving support, use the Add API.
Add Link
This is method is used mainly by users who are trying to add Read It Later support to an existing application that accepts custom services. For example, Google Reader's send to feature. If you have control over the application, using the API is the preferred method.
This opens a page on Read It Later and lets the user edit the page:
Replace the url (http://google.com) and title (Google) values with those of the page you are saving.