The CE-510 and 525 type ratings can be issued as single pilot required and will show as CE-510S or CE-525S. For the CE-500 type which covers the -550 also it is a logbook endorsement. From the FAA FSIMS -
“Each person who successfully completes the training and proficiency check identified in the exemption must have their pilot logbook endorsed by the operator’s instructor administering the training, using the following endorsement:
“I certify that (first name, MI, last name) has successfully completed the CE-500 single-pilot training curriculum conducted by (Name of Company) for the (model-specific type, e.g., CE-550) identified in Exemption No. xxxxx, as amended.” /s/ [date] J. J. Jones 987654321CFI Exp. 03-31-16”