Officials in Montgomeryville want to be ready with financing for the proposed multi purpose community center should the township supervisors decide to undertake the project at Stump and Horsham Roads.   They have hired the bond underwriting firm RBC Capital Markets to sort out the available options.   RBC worked with the township sewer authority on refinancing a $6,700,000 bond issue last year and saved ratepayers a significant amount of interest cost.   The bond consultant will meet with the township finance committee on September 27th.