You can probably get by with a USE PERMIT. Here is an excerpt from the PFBC site:
UNPOWERED BOATS
Unpowered boats are not required to be registered - unless used at a Fish & Boat Commission access area or lake, or at Pennsylvania state park lakes; or required by the owner (one example is the U.S. Army Corps of Engineers).
....view list of Commission access areas
....view DCNR's listing of PA state parks
....go to our Registration page to find out how to register or title a boat.
Another option for unpowered boats (only) is a Use (Boat Launch) Permit from the Fish & Boat Commission, or a Launch or Mooring Permit from the Department of Conservation and Natural Resources Bureau of State Parks....view issuing agents for Use Permits.
Permits can also be purchased online using a credit card at The Outdoor Shop....go to The Outdoor Shop (choose Products, then Boat Permits)
Visit this page for a complete understanding of the rules:
http://www.fish.state.pa.us/registration.htm
Note that other lakes may have special boating and launching rules. For instance, Cross Creek Lake out our way is a County Park and requires its own launch permit, though I am not sure if Kayaks are covered.
If it is a PFBC Lake or State Park, the general USE PERMIT probably suffices. Anywhere else, you may need to check with the lake owner (County, Township, Army Corps, etc.).