The party said the UK Government should work with all banks on how they can pool together to keep at least one branch open in communities to maintain face-to-face services.
The issue was debated on the second day of the Lib Dems’ spring conference in Aviemore as RBS plans to close 52 of its branches across Scotland.
The bank, which is majority-owned by the taxpayer, originally intended to close 62 premises, however 10 rural branches were given a reprieve, allowing them to remain open until the end of 2018, with an independent review on their long-term future.
The Lib Dems also backed calls for UK ministers to use their major shareholding in the bank to halt the remaining closures, and take a more community-orientated approach.
In addition, the party voted in favour of establishing a “rapid-reaction service”, to bring together public agencies to explore how community assets such as bank branches can be maintained.
The mechanism, which could be introduced by the Scottish Government, would allow communities, through their local authorities, to activate the service if they felt crucial local services were in jeopardy.
Community groups should also be given a “fair chance” to buy out assets of local value, the Lib Dems said.
The party has launched a petition on the proposals.
Jamie Stone, MP for Caithness, Sutherland and Easter Ross, said: “Losing local RBS branches is a major blow to people and businesses across Scotland.
“It’s an easy cost-saving strategy for banks but it’s devastating for rural communities.
“Our local economies deserve busy high streets and face-to-face reliable banking.
“That’s why setting up banking hubs, where banks could pool resources to ensure at least one shop can stay open, is an innovative solution to the daunting programme of closures on the horizon.
“The UK Government must give these proposals serious consideration. There should be a mechanism for people to intervene when services in their towns are threatened.”