I think M13K07 is a "plaque" forming phage. You can thus simply titrate your lysate an a lawn of an appropriate host. The plaques in this case are no real lysis plaques. They result from growth inhibition of the infected hosts, since M13 does not actually lyse the host . Look at the M13 page in wikipedia for instance. And it is easy to find protocols for titration on the web. Good luck!

I usually do the titrations with TG1 or XL-1Blue cells, but any infectable strain should be ok. I also plate on kanamycin plates for routine titrations. To achieve a good titration is important to make sure that you will have an excess of bacteria over phages, so every phage can infect one of them. This is achieved by going down to very high dilutions.  You should do several dilutions of M13 (I normally go from 10-4 to 10-12 in 500 microliters of media). Than I add to each dilution 500 microliters of exponentially growing bacteria for infection. After incubating at 37 degrees, I plate a small volume of each mixture on kanamycin plates. Lowest dilutions usually produce too many colonies, but higher dilutions get numbers that can be counted. If you are very careful doing dilutions and calculating the titers (taking into account the volumes used in each step), your titer should be ok. Several useful dilutions must produce comparable titers and you can calculate an average.