How can I finalise a DVD -R Disc?

I had a Samsung model 300E/XEU DVR/VCR recorder until the timer failed so I replaced it with a Toshiba DVD/VCR/HDD recorder.Ihave got several -R discs that are not full because I was still adding to them (holidays etc.)But now the Toshiba -R recorder will not accept these few discs because they are not finalised. How can I get these 7 discs finalised ?. Does anyone out there have a Samsung model 300E/XEU who is willing to finalise my 7 discs ?.I will gladly refund all costs and postage.