Plotting is the raison d'etre for telescopic observing. In any case, it's actually prefered that you don't make shower associations immediately at the eyepiece. Instead, simply plot what you see relative to the star background, as accurately as possible. The plotted trails allow objective criteria to be applied in assessing shower assignment. You will see far more if instead you choose a field 15 to 25 degrees away from the radiant point in the sky.
Some visual observers have their center of vision at major-shower radiants.
That's feasible because the unaided eye has a much wider field of view than telescopes. This goes down in major showers which have relatively few faint meteors, such as the Perseids. You can read up on these basics via the Web . Instructions on plotting can be obtained at the American Meteor Society's Web site, in Norman McLeod's Meteor Plotting . Proper gnomonic charts can be obtained from the North American Meteor Network and from the International Meteor Organization .