The 46-year-old went missing from Scarborough on Wednesday May 8.
A public search will take place tonight and those who wish to attend are asked to meet at The Mere Café, Scarborough, at 6pm.
On the Facebook page, it states: "We will all meet together to search a recommended place, if we all gather then split into two's and follow a route which has been decided we can cover all the area at the same time.
"If we can get enough people there then we could set a second lot off half an hour later covering the same area again.
"If we find nothing we can all move onto another area that has been recommended to us.
"It would be great to do a huge search involving as many people as possible. Please Help if you can."
People taking part are asked not to wear a blue hoody or baseball cap.
Peter, from Whitby, is described as a white, about 6ft 1in tall, and of muscular/athletic build, unshaven and his hair is a greying/brown colour which is slightly thinning.
He was last seen wearing a blue hoodie underneath a blue waist length jacket, loose grey cotton jogging bottoms, and blue Nike trainers. It is believed that he could also have been wearing a blue baseball cap (as pictured in the above image).
However, since his disappearance he may have changed into a pair of blue jeans.
Officers believe that he may be sleeping rough so may appear more dishevelled than in his pictures.
If you have seen Peter or know where he may be, please contact police on 101 and quote reference number 12190083137.