Thank you. I will contact support.
Just now I took a quick look into the (older) source code at GitHub: Basically the software should regard TIS-B data. There is a type definition in the header file dump1090.h. So, TIS-B data should be used by rbfeeder ...
/* Where did a bit of data arrive from? In order of increasing priority */
typedef enum {
SOURCE_INVALID, /* data is not valid */
SOURCE_MLAT, /* derived from mlat */
SOURCE_MODE_S, /* data from a Mode S message, no full CRC */
SOURCE_MODE_S_CHECKED, /* data from a Mode S message with full CRC */
SOURCE_TISB, /* data from a TIS-B extended squitter message */
SOURCE_ADSB, /* data from a ADS-B extended squitter message */
} datasource_t;