Are you coming back to Pennsylvania anytime soon? Doing this abroad makes it much more complicated. While I'm not sure about Dauphin County, I know most counties will require you to hire a lawyer in the foreign jurisdiction to submit an affidavit stating that your consent was validly given under the laws of that foreign jurisdiction. The court isn't going to do you the favor of determining whether the consent complies with the laws of the foreign country. In fact, my county's courts require that affidavit even when the consent is given in another state (e.g., Maryland).
Sending it back home to be witnessed isn't practical, because the witnesses are certifying that they were in your presence when you signed it, which wouldn't be true in this situation. Neighbors in the foreign country can witness it, but you would need to bring those individuals to the PA courts if the authenticity of your signature is ever challenged. This is hard to accomplish because subpoenas can't usually reach people in foreign countries.
In short, it would be a good idea to wait until you are in PA to take care of this. If that isn't an option, you should see an attorney in your local area who is willing to sign the affidavit. It can be filed in the Orphans' Court or sent to opposing counsel. Good luck!
You are voluntarily consenting to an adoption, In order for the document to be valid, it must be signed in front of 2 witnesses- and a notary public. If you have any questions, you should consult with an attorney to clearly respond to those questions. One item, frequently overlooked is the state's reunion registry. You can get that from the state's website. It is free, easy to fill out and I highly recommend that you sign and file it now. An easy detail to forget. Also, if you really want to do the child a huge favor, let the family you will always be available if they need medical information. That is the most important gift you can give a child. The attorney handling the adoption should furnish you with a medical family social history for you to complete. I encourage you to complete that. Best wishes,