I'm assuming you don't have access to the frame you bought?
If you don't, frames are usually made to fit centerline to centerline of the boat, maybe 2-4 inches wider.
Per the RMR website, your boat is 6'10" wide and uses 20" tubes. That would give you a CL to CL measurement of 62". An educated guess would put your frame at 62-66" wide. Bimini frames "spring" in or out 3" to accommodate various widths from one frame. I'd get bimini frame in 66" or thereabout.
While capt has the basic idea down and you could probably wing it with those numbers, DRE double rail frames are actually made a little wider than that. If you bought it from them, give them call on monday and they'll let you know the width.
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