rtlsdr provides CMake targets:

  find_package(rtlsdr CONFIG REQUIRED)
  target_link_libraries(main PRIVATE $<IF:$<TARGET_EXISTS:rtlsdr::rtlsdr>,rtlsdr::rtlsdr,rtlsdr::rtlsdr_static>)

rtlsdr provides pkg-config modules:

  # C Utility Library
  librtlsdr