Liberty Bells will indirectly also increase REF size.
(Through revolutionary rate.)
If I remember correctly though, it is only one of many factors.
(The taxes you pay to the king is another factor for example.)
Basically REF-calculation includes a mix of many different indicators for your colony becoming bigger and stronger.
(At least in NetBandit's REF calculation that is included in TAC and RaR.)
Thus I would not worry too much about "Liberty Bells increasing REF".
The benefits from Liberty Bells (Founding Fathers, increased City Radius, Production Bonus, ...) are much more important.