Conversion of vcf files to npf file format

It doesn't look like that there is a way how you could directly convert VCF contacts to a Samsung NPF backup. However, you can probably directly import VCF contacts or sync them with your Samsung device and perform the backup afterwards should you want it. Some older devices may accept only CSV instead VCF so you may try to convert that first using any of the available vcf to csv conversion options.

Open VCF file    Open NPF file