Depends on how much fruit flavour you want in your end product. Rasberry is pretty tart after the sugar has been fermented out, 1 can of puree might be just right, might be too much.
Found this product description online:
Vintner's Harvest Fruit Bases - Raspberry: An Oregon grown gem, bright red, medium sized berry with the familiar flavor. One 96 oz. can makes a fuller flavor and bodied 3 gallon batch or a lighter 5 gallon batch of wine. The 3- and 5-gallon batch recipes are included on the label.
After reading that, I'd say add 1/2 to primary & see if it's enough of a fruit profile for you, if not, add the rest of the fruit in increments till you get the flavour profile you want. I'd freeze the remaining puree in a sanitized tupperware bowl.
Regards, GF.