One of the best things about going on exchange is that you'll be able to take courses that you can't take at UCR. However, in order to graduate, you must still do at least 16 credits worth of UCR-approved courses. In order to make sure everything is accepted, there are two things you have to do.
Hand in the Learning Agreement
Once you have approval to go on exchange, you have been admitted to the location and you have chosen your courses, you have to hand in the Learning Agreement form. On this form you have to indicate which courses you are going to take and how many ECTS each course represents. You can also indicate whether a course is an equivalent to a UCR course and whether you would like to fulfil a certain graduation requirement with one of your courses. After you have filled in the form and all relevant instructors have signed the form, you must send the form to your tutor, who needs to sign it last. Finally, you need to send it to the Registrar, who will pass it on to Board of Examiners. They will use this form to evaluate your exchange request.

Please note that it is your responsibility to research the host universities credit system and make sure you are enrolled in the appropriate amount of course credits! On the form you may indicate where the Board of Examiners can find this information.
Arrange the transcripts
Before you leave your host university, make sure to request two copies of your transcript: one for your own records and one for UCR. Once the Registrar receives your transcript, the transfer of credits can be arranged, provided your completed Learning Agreement was submitted and reviewed by the Board of Examiners before the start of your semester abroad. If you ended up doing the courses as indicated on the Learning Agreement, there is nothing to worry about. If you switched courses during the semester, the BoE might ask for extra information.

To see how many credits you need to obtain at the host university, check the International Credit System overview.