Yes you can. They are designed to be pitchable. As the package states, open (smack) the nutrient packet 1-3 hours before you pitch. Making a starter will increase your pitch rate, but plenty of people have made great beer pitching a smack pack. I would wager most if not all homebrewers did not make a starter for their first brew, but I could be wrong.
Edit: Sorry..I didnt read thoroughly before answering. You said "Propagator" pack. This is designed to be made into a starter. I have never used these, sorry. Im sure someone has directly pitched this, but I can not attest to its success. I am making an assumption that it will be fine, but fermentation will take considerably longer. I am assuming the yeast cell count on these are low intentionally with the thought that they will reproduce in a starter before they are pitched.