I would definitely have them send a pic of the underside and a good one of the signature. Frankly I'm surprised they didn't include it if they are Roseville collectors or even know a little. I believe the majority of fakes can be ID'd in the signature (you probably want to look that up - I could be wrong). Lot's of knock offs out there so you are right to be wary.
Wendy can probably add more but for sure she'll want to see a good pic of the signature. If they are unwilling to provide, I wouldn't make the drive...
ETA: LOL... Others posting while I was
Haven't looked at Sapphires links yet but even if you find the pattern, you need to see the sig...
Also think I saw this info on Antiques Road Show. You also want to look for "coloring outside the lines" Another good way to spot a fake.