The accepted Rational Function（ RF） model application for satellite images is limited to transformations between object and image space. However

the use of the third-order RF model and of the 80 Rational Polynomial Coefficients（ RPCs） in the Radarsat-2 metadata extends its application from optical images to Synthetic Aperture Radar（ SAR） images. We provide a brief overview of the generation process and properties of multiple SAR RPC products

with special emphasis on the processing chain of basic SAR products in combination with orbit model approximation. Finally

we validate new types of RPC geometric performance experimentally. We consider the different basic products of Terra SAR-X

the COSMO-Sky Med of the Guangzhou area（ in China）in stripmap mode as test data and demonstrated the effectiveness of the RF model for the geometric processing of SAR images.