Reliance Controls lists the breakers that can be used in their spec sheet which we have a link to under the specs tab on the product page.
The spec sheet lists the following breakers as being acceptable:
"THE FOLLOWING CIRCUIT BREAKERS ARE UL LISTED FOR USE WITH ALL TR
TT, T1 AND T2 SERIES TRANSFER PANELS:
SIEMENS TYPES QP, QT, QPH, HQP, QPF, QPHF, QFP, QE, QEH
SQUARE D: SERIES HOM (100A Maximum)
CH/WESTINGHOUSE: SERIES BD, BR, BQ, GFC (All 100A Maximum)
MURRAY: TYPE MP"
Spec Sheet