To combine all your CSV contacts into one VCF file , it is easiest to first convert that CSV into vCard format. One option is to use a tool like
WholeClear CSV to VCF Converter. You will load your CSV file in and preview the contact list . You will map each field (name, phone, email, etc.) to the appropriate vCard properties, and when exported the software will create a unified VCF file . Combining your contacts into a single file eliminates dealing with importing multiple, individual vCards , and works great for Android, iPhone , or iCloud, and any contact app without losing information.