Hi Donald
As it's a lithographic print, you should have no trouble dampening it and then flattening it under pressure. Make sure the pencil is 'lead' pencil (i.e. graphite) and not some coloured number, before you do this. Lead pencil is just fine.
My preferred way to humidify small items in preparation for flattening is as follows:
What you will need: A tray large enough to hold your print with space around it, and with walls (something like a large casserole dish is good); a rack to fit inside this and which is big enough to put the print on top of; some clean, lint free cloths such as teatowels; newspapers; a heavy book or board; plastic wrap or a large plastic bag to put over the tray once the print is in it.
Step 1: Place a damp (i.e. wet and very well wrung out) tea towel or towel flat in the bottom of the tray.
2: Place rack on top.
3: Place a clean, dry teatowel on the rack, making sure the edges don't hang down to the wet cloth, otherwise the dry towel will soak up the water from the wet one.
4: Place the print face up on the dry tea towel.
5: Cover the lot with plastic so that it is well sealed. Make sure the plastic does not droop onto the print. If you have a sheet of glass or perspex that will cover the tray, use that instead.
6: Wait until the print feels cool and damp to the touch. This could take anywhere from half an hour to several hours to overnight. Don't worry - you can't get it too wet with this method.
7: Make a stack of very flat newspapers (2 or 3 tabloid sized papers should do) with two or three very clean, very flat tea towels on top of these.
8: Remove print by lifting the towel it's sitting on. This will support it and prevent it tearing. Place print face down on your stack of papers and towels.
9: if you can remove the teatowel the print was sitting on, do so. If you feel it's stuck, just leave it there.
10: Place another stack on top of the print - first some tea towels, then a paper or two, and then a large board or book to apply pressure.
11: Leave this for at least 24 hours (preferably 48) to dry and flatten.
Hope that helps!
Cheers
Prue